Fast Client-Side Utilities
Free, fast, and completely secure web tools. We protect your data by processing everything directly in your browser.
Start with a specific job
These are separate tools, each doing one job in your browser. The full catalogue is below, and every category has its own page.
JSON Formatter
Beautifully format, validate, compress and sort JSON data locally.
Image Compressor
Reduce the size of images (PNG, JPEG, WebP) locally in the browser without losing quality.
Merge PDF Files
Combine several PDF files into one document in your chosen order, entirely in the browser.
Word Counter
Count words, characters, sentences and paragraphs live as you type, with reading and speaking time estimates.
QR Code Generator
Create custom QR codes from links, texts and Wi-Fi networks locally in the browser.
Metronome
Click from 30 to 240 BPM with a choice of beats per bar, note values, tuplets, and tap tempo.
Age Calculator — How Old Am I?
Exact age from a birth date to today, in years, months and days, plus days until the next birthday. For age on a past test date use Chronological Age; to turn an age into a birth year use Birth Year.
Ohm's Law Calculator
Enter any two of voltage, current, resistance, and power, and the page fills in the other two.
Case Converter
Rewrite text as sentence case, upper case, lower case, title case, a slug, or alternating case.
Base64 / Hex / Binary Multi-Coder
Convert text or binary files to Base64, Hexadecimal, Binary representation and back.
Cryptographic Checksum Hash Generator
Generate and compare multiple cryptographic hash checksums (MD5, SHA-1, SHA-256, SHA-512) for text and large files locally.
All tools
Age Calculator — How Old Am I?
Exact age from a birth date to today, in years, months and days, plus days until the next birthday. For age on a past test date use Chronological Age; to turn an age into a birth year use Birth Year.
Online Alarm Clock
Set a wake-up time and get a live countdown, a looping generated melody, a full-screen notice and a blinking tab title when the moment arrives — right in the browser tab.
Audio Analyzer
Measure sample peak, an interpolated true peak, RMS, a simple LUFS figure, and stereo correlation for an audio file.
MP3 to WAV / WAV to MP3
Local audio conversion between MP3 and WAV directly in the browser without downloading to the server.
Audio Key Detector
Guess a major or minor key from an uploaded recording by tracking a pitch and scoring it with Krumhansl-style profiles.
Merge Audio
Decode two or more audio files, place them one after another, and download a 16-bit WAV.
Audio Normalizer
Equalize the volume level of audio files to the optimal standard without losing quality.
Audio Scale Converter
Convert one level between dBFS, percent, and linear amplitude, and print all three.
Audio File Spectrogram
Draw a Hann-windowed spectrogram of an audio file, with a start and end time and a choice of FFT size.
Audio Speed and Pitch
Flexibly change playback speed and audio pitch locally in the browser.
Trim Audio
Cut a start and end time from an audio file and download that slice as 16-bit WAV.
Base64 / Hex / Binary Multi-Coder
Convert text or binary files to Base64, Hexadecimal, Binary representation and back.
Calculator
Evaluate one arithmetic expression with parentheses, powers, percent, and the listed functions, in degrees or radians.
Bass Guitar Scale Fingering
Scale patterns for 4-string bass by position: one-finger-per-fret or Simandl 1-2-4 fingering, with roots, note names and degrees on the fretboard.
Violin, Cello and Double Bass Scale Fingering
First-position scale fingerings for violin, viola, cello, and double bass: which finger plays each note, on which string, with low and high placements marked.
Tap BPM Counter
Tap the button or the space bar and read BPM from the average gap between your taps.
Bra Size Calculator & Converter
Estimate your bra size from underbust and bust measurements, or convert an existing size between US, UK, EU, FR and IT — plus its sister sizes.
Business Days Calculator
Count weekdays between two dates, skipping Saturdays, Sundays, and any holiday dates you paste.
Monthly Calendar Generator
Draw one Gregorian month as a seven-column grid, starting the week on Monday or Sunday, and print that grid.
Case Converter
Rewrite text as sentence case, upper case, lower case, title case, a slug, or alternating case.
Charades Word Generator
Deal charades words from a no-repeat deck: six categories, easy and hard levels, and a built-in round timer with a beep.
Chord Key Finder
Score the twelve major and twelve minor keys against a list of chord symbols and show the best five.
Clothing Size Converter
Convert clothing sizes between US, UK, EU, Italian, French, Japanese and international S–XXL scales for dresses, shirts, suits and trousers.
Code Formatter
Fast alignment and formatting of HTML, CSS, JavaScript and TypeScript code offline.
Coin Flip — Flip a Coin Online
Flip a virtual coin with a 3D animation, fair crypto randomness, and a running heads/tails counter.
Collage Maker
Place images on standard paper sizes (A4, A3, Letter) for printing.
Color Palette Generator
Create harmonious color palettes from a base color and export CSS codes.
Color Code Translator & Contrast Matrix
Convert two hex colors to sRGB, CIE LCh, a WCAG contrast ratio, and a row of LCh mixes.
Concrete Calculator — Bags Needed for Slabs, Footings & Posts
Work out how much concrete a slab, footing, column pour or a batch of fence post holes needs: pick the shape, enter its real dimensions, and get the volume in cubic yards and cubic meters plus the number of pre-mixed bags to buy.
Countdown Timer
Count down from the minutes and seconds you set, and play a short tone at zero.
Cron Validator
Offline syntax checking of Cron expressions with human-language interpretation of the schedule.
CSS Flexbox Generator
Build a CSS flexbox layout visually: flex-direction, justify-content, align-items, flex-wrap and gap on the container, plus per-child flex-grow, flex-shrink and flex-basis, all with a live preview and copyable CSS.
CSV Validator
Check that every non-empty CSV row has the same number of comma-separated fields as the first row.
Add or Subtract Dates
Move a calendar date forward or backward by a chosen number of days, weeks, months, or years.
Day of the Week Calculator
Name the weekday of a calendar date and give its day-of-year number and how many days remain after it.
Dice Roller
Roll 1 to 12 six-sided dice. Each face comes from a cryptographic random word, and you can reroll a subset.
Dockerfile Validator
Check a Dockerfile for an uppercase instruction, a FROM line, and a small set of argument shapes.
Drawing Word Generator
Deal easy-to-draw words for sketching party games: a difficulty filter, a skip counter and an optional 60-second sketch timer.
Elden Ring Runes Calculator
Sum Elden Ring level-up costs from your level to a target up to 713, then divide by stored farming yields.
ENV Validator
Check a .env file for KEY=VALUE rows, duplicate keys, and quotes that open and do not close.
EXIF Viewer — View & Remove Photo Metadata
Inspect EXIF metadata of JPEG and PNG photos — camera, date, GPS location — and download a clean copy with all metadata removed.
Fantasy Name Generator
Generate fantasy names for elves, dwarves, orcs, humans, dragons and wizards from race-specific syllable tables — with gender and surname options.
Favicon Generator
Generate a complete favicon set — PNG 16/32/48/180/192/512 plus favicon.ico — from any image, right in your browser.
Gamepad Tester
Test any controller online: press buttons to light them up, watch live stick crosshairs, measure stick drift against a deadzone circle and try vibration.
Genshin Impact XP Calculator
Estimate Adventure Rank experience from this page's fixed table, from AR 1 through the start of AR 60.
Guitar Scale Fingering
Map any scale onto the guitar fretboard by position: fingers 1-4, root markers, and the positions that cover the whole scale — for classical and any six-string guitar.
Cryptographic Checksum Hash Generator
Generate and compare multiple cryptographic hash checksums (MD5, SHA-1, SHA-256, SHA-512) for text and large files locally.
HEIC to JPG Converter
Convert iPhone HEIC/HEIF photos to JPG or PNG instantly in your browser — no upload, no app, no account.
HTML Table Generator
Build an HTML table visually by clicking cells and typing — get clean, semantic table markup with a live preview, no format to paste or convert.
HTML & URL Encoder / Decoder
Encode or decode with encodeURIComponent, or escape the six HTML characters this page maps.
HTML Validator
Check that HTML tags nest and close, and that quotes inside a tag are finished.
Image Border & Rounded Corners
Add a colored border and round the corners of any picture, with a live preview right in your browser.
Image Color Picker
Pick any color from a photo right in your browser: a zoom loupe magnifies the pixels, one click gives you HEX, RGB and HSL codes to copy.
Image Compressor
Reduce the size of images (PNG, JPEG, WebP) locally in the browser without losing quality.
Image Converter
Quickly convert images between PNG, JPEG, WebP, GIF, BMP offline in the browser.
Image Cropper
Crop images with a handy selection box locally in the browser.
Image Resizer
Change the width and height of images in pixels or percentages locally and securely.
Steganography Hidden Image Encoder
Hide confidential text messages inside image pixels using LSB encoding or recover data from encoded PNG files offline.
Image to Text Converter (OCR)
Extract text from images with OCR directly in your browser: JPG, PNG, WebP and BMP in 12 recognition languages.
Images to PDF Converter
Turn JPG, PNG, WebP or BMP images into a single PDF with page size, margins and orientation control.
INI Validator
Check INI text for sections, key=value lines, comments, and duplicate names. It does not look for HTML tags.
Guitar and Ukulele Tuner
Tune guitar, ukulele, bass, violin, and mandolin with live microphone pitch detection.
Interval Ear Trainer
Hear two live-synthesized notes, name the musical interval, and let adaptive difficulty focus practice on your weakest intervals.
JSON Diff Checker
Compare two JSON payloads by structure, not by text: see every added, removed and changed key on its own path, entirely in your browser.
JSON Formatter
Beautifully format, validate, compress and sort JSON data locally.
JSON Schema Validator
Check one JSON value against a small subset of JSON Schema: types, ranges, required keys, properties, items, pattern, and enum.
JSON Validator
Check JSON structure and configurations for errors offline in the browser.
JWT Token Debugger
Decode a JWT header and payload, and compare the signature with HMAC-SHA256 of the secret you type.
Key Chord Builder
Build the diatonic chords of a selected key and label every degree with its harmonic role.
Keyboard Tester
Press any key and watch it light up on an on-screen keyboard: check every switch, count simultaneous keys and spot dead or chattering keys.
LC Resonance Calculator
Find the resonant frequency of an LC pair, plus XL, XC, and the net reactance at a test frequency.
LED Resistor Calculator
Find the series resistor for one or more LEDs from the supply, the forward drop, the count, and the current.
Lorem Ipsum Generator
Generate classic lorem ipsum placeholder text as paragraphs, sentences, or words right in your browser.
Magic Bytes & Binary Header Doctor
Inspect file magic signatures, view raw hex/ASCII headers, and repair corrupted binary file headers client-side.
Meat Cooking Time Calculator
Estimate roasting time for turkey, chicken, beef, pork, ham and lamb from weight and oven temperature, with USDA safe internal temperatures and rest times.
Metronome
Click from 30 to 240 BPM with a choice of beats per bar, note values, tuplets, and tap tempo.
Minecraft XP Calculator
Turn Minecraft levels into experience points with the game's own level formulas, then into mob kills and ore counts.
Random Fake Data & Mock API Generator
Produce realistic mock datasets including names, emails, addresses, companies, and credit cards fully offline.
Morse Code & Cipher Playbook
Encode and decode Morse, plus a Caesar shift, ROT13, and a Vigenère shift, with a tone for the Morse you just encoded.
Mouse Sensitivity Converter
Convert sensitivity with a fixed yaw per game, and read eDPI and centimeters per 360 degree turn.
Mouse Tester
Test every mouse button online: left, right, middle and side buttons light up on a mouse graphic, with press counters, a scroll check and a double-click detector.
NATO Phonetic Alphabet Converter
Spell any text using the NATO/ICAO phonetic alphabet (Alfa, Bravo, Charlie...) live as you type, plus a full A-Z and digit reference table.
Nether Portal Calculator
Convert coordinates between the Overworld and the Nether (÷8 / ×8) and link your Minecraft portals precisely.
Notepad Calculator
Keep notes and math on the same page. Lines with an expression are evaluated, and the results are totaled.
Numbers to Words
Spell a non-negative number in English words, with an optional dollar, euro, or hryvnia name, on every page except the Ukrainian one.
Office Table Converter
Convert data between CSV, TSV, HTML, Markdown and JSON without uploading to the server.
Ohm's Law Calculator
Enter any two of voltage, current, resistance, and power, and the page fills in the other two.
One Rep Max (1RM) Calculator
Estimate your one rep max from any set of 2–12 reps using four proven formulas, and get your training percentages from 50% to 95%.
Op-Amp Gain Calculator
Compute ideal inverting or non-inverting op-amp gain from the input resistor and the feedback resistor.
PCB Trace Width Calculator
Estimate an external or internal PCB trace width from current and temperature rise, then the resistance of the length you type.
PDF Compressor
Reduce the size of PDF files by optimizing images and fonts locally.
Merge PDF Files
Combine several PDF files into one document in your chosen order, entirely in the browser.
PDF to JPG Converter
Render every page of a PDF to a JPG or PNG image in the browser, with adjustable resolution and quality.
Piano Scale Fingering Chart
See the standard fingering for any major or minor piano scale on an interactive keyboard — right hand, left hand, one or two octaves, with thumb-under crossings marked.
Pomodoro Timer
Stay focused with timed work sessions and automatic short and long breaks, complete with a gentle beep and a live countdown in the tab title.
QR Code Generator
Create custom QR codes from links, texts and Wi-Fi networks locally in the browser.
QR Code Scanner
Decode a QR code from a photo or the camera with jsQR, and copy the text it contains.
Random Name Picker
Pick random winners from a pasted list of names — remove winners after each draw, draw several at once, and go fullscreen for classroom or raffle displays.
Random Word Generator
Generate random English words filtered by part of speech, starting letter, and length — nouns, verbs, and adjectives from a curated 1,180-word list.
RC High-Pass Calculator
Find the cutoff of a first-order RC high-pass and the gain, attenuation, and phase at the frequency you type.
RC Low-Pass Calculator
Find the cutoff of a first-order RC low-pass and the gain, attenuation, and phase at the frequency you type.
Realtime Spectrum Analyzer
Watch a live Hann-windowed FFT of the microphone, from 512 to 8192 points, on a linear or log frequency axis.
Refresh Rate Test
Measure the refresh rate your browser really renders: a live Hz readout from frame timestamps, a frame-time graph, a skipped-frame counter and a UFO-style smoothness test.
Replace in Text
Replace a literal or a /pattern/flags match, with an optional case-preserving replacement.
Resume Builder
Fill in your contact details, summary, experience, education and skills to generate a clean, single-column, ATS-friendly resume PDF — entirely in your browser.
Rhythm Sight-Reading Trainer
Practice reading and tapping random rhythms with real, measured timing-accuracy feedback.
Rounding Calculator
Round any number to any place value — from millions to ten-thousandths — with exact digit-by-digit math and a clear explanation of the result.
Find in Text
Find a literal string or a /pattern/flags expression and list each hit with its line, index, and a short context.
Signature Generator
Draw or type your signature online and download it as a transparent or white-background PNG — free, right in your browser.
Remove Silence from Audio
Automatically find and cut silence and long pauses from your audio recordings.
SQL Formatter
Format and beautify SQL queries or minify them to one line — entirely in your browser.
Stopwatch
Start, pause, and lap a clock that reads elapsed time from performance.now and paints hundredths of a second.
Guitar & Bass String Tension Calculator
Calculate the real pulling tension of a guitar or bass string in lbs, kg, and Newtons from its gauge, your scale length, and the target note.
Subtitle Converter
Convert subtitles between SRT and VTT, shift their timing by milliseconds or seconds, and renumber cues — privately in your browser.
SVG to PNG Converter
Rasterize any SVG file into a crisp PNG at an exact target resolution, with a transparent or solid background and one-click 1x/2x/3x batch export.
Text Diff
Compare two texts side by side, line to line, and see every added and removed line highlighted, privately in your browser.
Text to Speech
Speak your written text using natural browser voices and save the audio.
Time Duration Calculator
Hours and minutes between two clock times — overnight included — plus adding or subtracting hh:mm durations.
Time Zone Converter
Convert a local date and time between any two IANA time zones with daylight-saving rules applied.
TOML Validator
Check TOML-like lines for section headers, key = value pairs, duplicates, and simple quotes and brackets.
Tone Generator
Render a sine, square, sawtooth, or triangle tone from 20 Hz to 20 kHz and download it as WAV.
TSV Validator
Check that every non-empty TSV row has the same number of tab-separated fields as the first row.
Typing Speed Test — Free WPM Test
Measure your typing speed in WPM with live word highlighting, accuracy percentage, and error count.
Ukulele Chord Diagrams
Type any chord name and see every playable ukulele chord shape in standard GCEA tuning — a real voicing search, not a static lookup chart, with every match you can page through.
Unix Timestamp Converter
Convert a local date and time in a chosen IANA zone to Unix seconds, or read a seconds or milliseconds value back.
Video to MP3 Converter — Extract Audio from Video
Extract the audio track from MP4 or WebM video and save it as MP3 or WAV — entirely in your browser, no upload.
Video Trimmer — Cut Video Online
Trim a video to the exact segment you need directly in your browser — sliders with frame preview, no upload, no watermark.
Voice Recorder
Record the microphone with MediaRecorder, play the take back, and download WebM or the type your browser supports.
Voltage Divider Calculator
Compute the unloaded and loaded output of a two-resistor divider, plus the current and the power in each resistor.
WASM Section Inspector and Demangler
List the sections inside a .wasm binary and turn Itanium _ZN symbol names into namespace paths, in the browser.
Audio Waveform Visualizer
Decode an audio file and draw the first channel as a min/max waveform, with duration, channel count, and sample peak.
Webcam Test
Check your webcam online: live preview, real resolution and frame rate readout, and a PNG snapshot — fully in your browser.
ISO Week Number Calculator
Read the ISO week number, the ISO week-year, and the Monday–Sunday span of any calendar date.
Weight Converter
Convert weight and mass units instantly: milligrams, grams, kilograms, tonnes, ounces, pounds and stone.
What Is My Browser
See your browser name and version, operating system, rendering engine and full user agent string the moment the page loads — detected locally.
Wheel Spinner
Spin a wheel whose slice sizes follow the weights you type, and read the label under the top pointer when it stops.
Word Counter
Count words, characters, sentences and paragraphs live as you type, with reading and speaking time estimates.
Words to Numbers
Turn English number words into an integer: zero through nineteen, the tens, and hundred through trillion.
World Clock
Show the current civil time in several IANA zones, updated every second, starting from your zone plus three fixed ones.
XML Validator
Check that XML is well-formed: prolog version, matched tags, and closed quotes.
YAML Validator
Check YAML-like lines for indentation, keys, duplicates, and quotes. This is not a full YAML 1.2 parser.
ZIP Creator — Make a ZIP Archive Online
Pack any files into a single ZIP archive with your chosen compression level, entirely in the browser.
More tools
The rest of the catalogue. Each tool still runs in your browser.
20-20-20 Eye Strain Timer
A live background timer for the American Optometric Association's 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds, with a real 20-second break countdown when it's time.
555 Timer Calculator
Calculate astable frequency, duty cycle, charge and discharge time, or monostable pulse width for a 555 timer.
Add Line Numbers
Prepend sequential numbers to every line of a list or text instantly and privately in your browser.
Add Prefix and Suffix to Lines
Wrap every line of a list with custom prefix and suffix text instantly and privately in your browser.
Add Watermark to Photo
Free watermark maker: stamp text or a logo on one or many photos at once, right in your browser.
AES-256 File Encryptor
Password-protect any file into a portable AES-256-GCM encrypted bundle, and decrypt it back later with the same password, entirely offline.
AES-GCM Secure Encrypted Notepad
Author, encrypt, and decrypt custom text files locally using secure AES-GCM 256-bit password-based encryption.
Air Fryer Converter — Oven to Air Fryer Settings
Convert oven temperature and time to air fryer settings (or back), using the standard −25°F/−15°C, 20-25% less time rule of thumb, plus a lookup table for common foods.
Anagram Solver
Find exact anagrams of a word or discover every word you can make from a set of letters, checked against an English dictionary word list.
Angel Number Meaning
Decode a number you keep seeing — 111, 12:12, 777 — digit by digit, with its core number and repeating patterns.
Area Converter
Convert area units instantly: square millimeters to square kilometers, hectares, square feet, square inches and acres.
Aspect Ratio Calculator
Calculate the missing side for any aspect ratio — 16:9, 4:3, 21:9, 1:1 or custom — or simplify the ratio of two known dimensions.
Average Calculator
Paste a list of numbers and get the mean, median, mode, range, sum, min and max at once — or compute a weighted average with full steps.
BAC Calculator (Widmark Formula)
Estimate blood alcohol content from your drinks, body weight, sex and time elapsed using the classic Widmark formula, with every number shown — for education only, never for deciding whether to drive.
Band Name Generator
Generate ten band name ideas per click from curated word lists, with rock, metal, indie and punk flavor packs and click-to-copy.
Barcode Generator
Generate Code 128, EAN-13, EAN-8, UPC-A and Code 39 barcodes with live validation and automatic check digits, downloadable as SVG or PNG.
Bingo Card Generator
Turn any 24+ item list — or a built-in Christmas, baby shower or icebreaker set — into unique 3x3, 4x4 or 5x5 bingo cards, ready to print.
Biorhythm Calculator
Plot your physical, emotional and intellectual biorhythms around any date on an interactive chart.
Birth Year Calculator
The reverse of the Age Calculator: you enter an age and get the birth year, or both years if you are not sure the birthday has passed. It does not take a birth date and does not count days until a birthday.
Birthday Compatibility Calculator
Compare two birth dates by numerology: life path numbers, concord groups and a compatibility score.
Blur Image
Blur or pixelate selected parts of a photo by drawing rectangles over them — locally in your browser.
BMI Calculator
Calculate your Body Mass Index in metric or imperial units and see your WHO category on a color scale, entirely in your browser.
Body Fat Calculator (US Navy Method)
Estimate your body fat percentage from tape measurements with the US Navy method, see your ACE category and fat/lean mass — right in your browser.
Body Frame Size Calculator
Find your skeletal frame size — small, medium or large — from height and wrist circumference using the classic height-to-wrist ratio heuristic, right in your browser.
Border Radius Generator
Design CSS border-radius visually: four independent corner sliders in px or percent, a link-all-corners shortcut for instant circles and pills, plus an organic blob mode with randomized shapes.
Break-Even Calculator
Find the exact unit volume and revenue where fixed and variable costs stop exceeding sales, with a margin-of-safety readout and a revenue-vs-cost chart.
Caffeine Half-Life Calculator
Model how caffeine from your coffee, tea or energy drink decays over the next 12 hours and see how much is likely left when you go to bed.
Calorie Calculator (BMR & TDEE)
Calculate your BMR, TDEE and daily calorie targets for weight loss, maintenance or gain with the Mifflin-St Jeor formula — right in your browser.
Cat Age Calculator (Cat Years to Human Years)
Convert your cat's age to human years with the AAHA/AAFP veterinary scale and see its life stage from kitten to geriatric — entirely in your browser.
Certificate & CSR Decoder (X.509 / PKCS#10)
Paste a PEM-encoded X.509 certificate or PKCS#10 CSR and see every field decoded — subject, issuer, validity, SANs, public key and fingerprint — entirely offline.
Certificate Generator
Create a print-ready certificate of achievement or completion — recipient name, course title, issuing organization, date and a signature line, drawn as a real vector design entirely offline.
Character Counter
Live character count with platform limits: Twitter/X, Instagram, LinkedIn, YouTube titles, meta descriptions and real SMS segment math.
Child Growth Percentile Calculator (LMS Method)
Estimate a child's height or weight percentile using the real LMS statistical method behind official growth charts — entirely in your browser.
Chinese Zodiac Calculator
Find your Chinese zodiac animal, element and yin-yang polarity — with the Lunar New Year boundary handled correctly.
Chmod Calculator
Convert Linux file permissions between rwx checkboxes, octal numbers and symbolic notation with a ready chmod command.
Chord Chart Transposer
Paste a chord chart with lyrics and shift every chord by semitones, with a real chord-symbol parser and enharmonic-aware sharp/flat spelling.
Chroma Key Remover
Pick a flat green screen, blue screen or solid background color with an eyedropper and make it transparent, using real YCbCr chroma-distance keying.
Chronological Age Calculator (Y;M;D)
Age on a date you choose, written as clinical Y;M;D (for example 8;3;14), with the borrow steps shown. Unlike the Age Calculator, the reference date is not locked to today and there is no birthday countdown.
Circle Calculator
Enter any one measure of a circle — radius, diameter, circumference or area — and get the other three instantly, with every formula shown with your numbers substituted in.
Code Minifier
Minify CSS, JavaScript, HTML or JSON in the browser: strip comments and whitespace, see the size saved instantly.
Color Blindness Simulator
See a photo, chart or screenshot the way someone with protanopia, deuteranopia, tritanopia or achromatopsia would, using published color-vision-deficiency transform matrices applied in linear RGB.
Color Format Converter
Convert any color between HEX, RGB, HSL and CMYK notation with a live preview swatch — right in your browser.
Compound Interest Calculator
See how an investment grows with compound interest: final balance, total contributed and interest earned, with a year-by-year growth table.
Connect Four AI — Play Against a Minimax Engine
Play Connect Four against a real AI opponent that searches the game tree with negamax and alpha-beta pruning, backed by a genuine center-weighted position heuristic — pick your color and difficulty and drop discs on an animated board.
Contact Sheet Generator
Automatically arrange a batch of photos into a uniform thumbnail grid with burned-in frame numbers or filenames — the classic photographer's contact/proof sheet.
Cooking Measurement Converter
Convert cups, tablespoons, teaspoons, milliliters, grams and ounces with real ingredient densities — because a cup of flour does not weigh a cup of sugar.
CPS Test — Click Speed Test
Measure your clicks per second in a kohi-style click test with a live counter and an animal rank from turtle to cheetah.
Crontab Generator
Build cron expressions with dropdowns and instantly see a plain-language schedule plus the next 5 real run times.
CSS Animated Gradient Border Generator
Generate a smoothly rotating rainbow gradient border that correctly respects border-radius, built with @property, conic-gradient and mask-composite — copy the real CSS, watch it spin live.
CSS Box Shadow Generator
Build CSS box-shadow code visually: sliders for offset, blur, spread, color with opacity, inset mode and up to four layers with a live preview.
CSS Clamp() Calculator
Compute a real fluid CSS clamp() value from a min and max size across two viewport widths, with the slope and intersection shown step by step and a live resize preview.
CSS Clip-Path Generator
Draw arbitrary polygon shapes — including concave notches — by dragging points on a live preview box or your own uploaded image, and copy the resulting CSS clip-path: polygon(...) value.
CSS Filter Generator
Build a reorderable chain of CSS filter() and backdrop-filter() functions and preview it live on your own uploaded photo, with a copyable CSS line and PNG export.
CSS Gradient Generator
Build CSS gradients visually: linear, radial or conic type, angle slider and up to six color stops with a live full-width preview and copyable code.
CSS Grid Generator
Design CSS Grid layouts visually: set columns, rows and gap, then type area names into cells to build grid-template-areas — with a live preview and copyable CSS and HTML.
CSS Keyframe Animation Generator
Build real @keyframes animations on a multi-track timeline — transform, opacity and background-color stops per track — with a draggable playhead that shows the exact interpolated mid-animation state.
CSS Pattern Background Generator
Build tileable stripes, dots, checkerboard, grid, diagonal crosshatch and triangle backgrounds from real layered CSS gradients — zero images — or export the same pattern as an SVG <pattern> for use inside SVG documents.
CSS Scrollbar Generator
Style a scrollbar's width, track, thumb and hover color, then see the real WebKit result next to the real Firefox result — two genuinely different browser systems, side by side.
CSS Text Effects Generator
Type your own text and preview real neon-glow, 3D-extrude, letterpress, outlined and gradient-fill CSS effects live, with parameters computed by real math and a copyable CSS block.
Cubic Bezier Generator
Design a custom CSS cubic-bezier() timing function by dragging two control points, preview it live against a linear reference, then copy the ready value.
Curl Converter
Convert curl commands into ready-to-run Python, JavaScript fetch, Node axios, PHP and Go code — locally in your browser.
Daily Word Game — 5-Letter Word Puzzle
Guess today's secret 5-letter word in six tries. Everyone who plays on the same calendar date gets the same word, with real dictionary validation and Wordle-style color feedback.
Data Storage Converter
Convert data storage units instantly: bits, bytes, KB, MB, GB, TB and the binary KiB, MiB, GiB, TiB — with the 1000 vs 1024 distinction made explicit.
Date Difference Calculator
Calculate the exact distance between two calendar dates in days, weeks, months, and years.
Days Until Calculator
See how many days are left until any date or holiday — Christmas, New Year, Halloween, Valentine's Day or next Friday — counted live in your browser.
Dead Pixel Test
Fill your screen with solid white, black, red, green, blue and gray to spot dead or stuck pixels — plus a flashing fixer that may revive stuck ones.
Debt Payoff Calculator
Plan how up to five debts get paid off with the snowball or avalanche strategy: debt-free date, total interest, payoff order and the savings between the two.
Decking Calculator — Deck Boards & Joists Needed
Work out how many linear feet of decking boards and how many joists a deck needs, using real actual-vs-nominal lumber dimensions, a board expansion gap, standard 16in/24in on-center joist spacing, and a waste allowance for cuts.
Depreciation Calculator
Generate a full straight-line or declining-balance depreciation schedule for an asset, year by year, with a chart comparing both methods' book value over time.
Developer Secrets & Token Generator
Bulk generate cryptographically secure API keys, salts, tokens, and decode precise millisecond timestamps from UUIDv7.
Dice Notation Roller
A real tabletop dice notation parser: type 3d6+2, 4d6kh3 or adv and get every individual die roll, kept/dropped dice and the total.
Diceware Passphrase Generator — Random Word Passphrases
Generate strong, memorable passphrases built from random real words using the Diceware method — true cryptographic randomness, with the actual entropy in bits shown honestly.
Discount Calculator
Calculate the sale price after a discount, see how much you save, and stack a second discount on top.
Dog Age Calculator (Dog Years to Human Years)
Convert your dog's age to human years with two published models — the AVMA/AKC size-class table and the 2019 UCSD epigenetic formula — plus a life-stage label.
Drywall Calculator — Sheets & Screws Needed
Add up wall and ceiling sections — by length × height or a direct area, as many rows as you need — and get the number of standard 4×8ft or 4×12ft drywall sheets to buy, plus an optional honest rule-of-thumb screw-count estimate.
Electricity Cost Calculator — Appliance Running Costs
See what any appliance adds to your electricity bill: pick a device or enter watts, hours per day and your price per kWh to get energy use and cost per day, month and year.
ENV Diff Checker
Compare two .env files (staging vs. production, before vs. after a deploy) and see exactly which keys were added, removed or changed, with secret-looking values masked automatically.
Fancy Text Generator
Type once and copy your text in 14 Unicode font styles: bold, cursive, bubble, small caps, upside down, zalgo and more.
Fence Calculator — Posts, Rails & Pickets from a Linear Run
Work out how many posts, rails and pickets a fence needs from its total linear run: pick a post spacing, account for gates as a real deduction from the run, and get a materials count that honestly includes the classic "N spaces need N+1 posts" fencepost problem.
Find Duplicate Lines
See which lines repeat in any list or text — with exact counts, privately in your browser.
Firewood Cord Calculator — Stack Dimensions & Face Cord Conversion
Work out how many cords a stack of firewood is from its length, width and height — or convert 'face cords' (a.k.a. ricks) of a given log length into standardized full cords, since a face cord's size always depends on how the logs were cut.
Fraction Calculator
Add, subtract, multiply and divide fractions and mixed numbers, simplify them, and convert fraction to decimal and back — with steps.
Freelance Rate Calculator
Reverse-engineer the day rate or hourly rate you must charge as a freelancer or consultant from your target take-home income, overhead, taxes and realistic non-billable time.
Fuel Cost Calculator — Trip Cost by Distance & Consumption
Calculate how much fuel a trip needs and what it costs from distance, consumption (L/100km, km/L or MPG) and fuel price — with cost per passenger.
GCF & LCM Calculator
Greatest common factor and least common multiple of 2–10 numbers, with the Euclidean algorithm shown step by step and the prime factorization of every number.
Gematria Calculator
Compute the gematria of any word or phrase in Hebrew or Latin letters — six classic ciphers, entirely in your browser.
Gitignore Tester
Paste your .gitignore rules and a list of file paths to see exactly which files are ignored, by which exact rule and line, and which negation rules are silently dead because a parent directory is already ignored.
Glassmorphism Generator
Dial in a frosted-glass card — blur, tint, border highlight, corner radius and shadow — previewed floating over a genuinely animated background so blur quality is visible in motion.
GPA Calculator — Weighted Grade Point Average
Calculate your credit-weighted GPA from letter grades on the 4.0, 5.0 or 100-point scale, with instant conversion between scales.
Grade Calculator
Find the final exam score you need to reach your desired grade, or compute a weighted average of up to five grades.
Guitar Chord Diagrams
Type any chord name — Cmaj7, F#m7b5, G/B, anything — and get real, computed fretboard chord-box diagrams from a brute-force voicing search, not a static lookup image.
Half-Life Decay Calculator
Solve the exponential decay equation N(t) = N0 x (1/2)^(t/half-life) for any substance, isotope or drug you name — enter any three of remaining amount, initial amount, elapsed time and half-life, and it solves for the fourth with the rearranged formula shown step by step.
Hangman Game — Classic Word Guessing
Play classic Hangman in your browser: guess the hidden word one letter at a time before the stick figure is complete, with five word categories and full keyboard support.
HAR File Waterfall Analyzer
Upload a .har file exported from your browser's DevTools to see a real request waterfall built from each request's own timing data, plus checks for missing cache headers, uncompressed responses, and render-blocking scripts.
Hashtag Generator
Turn any post text into ready-to-paste hashtags: keyword extraction, CamelCase tags and a platform-aware counter.
Heart Rate Zone Calculator
Calculate your five heart rate training zones from age using the Tanaka formula, with optional Karvonen (heart rate reserve) targets from your resting pulse.
Hebrew Date Converter
Convert any Gregorian date to the Hebrew calendar and find when its Hebrew anniversary next occurs.
HMAC Generator & Verifier
Generate and verify HMAC message authentication codes with SHA-256, SHA-384, SHA-512, or SHA-1 using a secret key, entirely in your browser.
House Number Numerology
Find the numerological number of your house or apartment — including letters like 12B — and read what kind of home it makes.
HTML Accessibility Auditor
Paste raw HTML and get a real WCAG accessibility audit: a hand-built DOM walker checks images, form labels, heading order and link text, plus a genuine relative-luminance contrast-ratio calculator scored against the real AA/AAA thresholds — no external library, nothing sent anywhere.
IBAN Validator
Validate an IBAN's real ISO 7064 mod-97 checksum and cross-check its total length against a bundled per-country format table — entirely offline in your browser.
Ideal Weight Calculator
Calculate your ideal body weight from height and sex with four classic formulas — Devine, Robinson, Miller and Hamwi — plus the healthy BMI range, right in your browser.
IEEE-754 Float Visualizer
See exactly how a decimal number is stored as an IEEE-754 float — sign bit, exponent bits and mantissa bits — and why numbers like 0.1 aren't stored exactly.
Image Diff Checker
Upload two images and see a pixel-accurate visual diff between them, with perceptual YIQ comparison and anti-aliasing-aware highlighting — 100% local in your browser.
Image Dithering
Apply real Floyd-Steinberg, Atkinson or Bayer ordered dithering to any photo and reduce it to a 1-bit, 4-shade or reduced-RGB palette — a genuine retro/halftone look, processed locally in your browser.
Image Palette Extractor
Extract the real color palette of any photo in your browser: median-cut quantization finds 3–12 key colors with HEX codes, CSS variables and JSON export.
Image to ASCII Art Converter
Turn any photo into real ASCII art in your browser: real per-cell luminance sampling maps every patch of the image to a text character, in plain monochrome or colored HTML spans.
Image Upscaler
Enlarge an image 2x, 3x or 4x using real Lanczos or bicubic convolution resampling, shown honestly side by side against the browser's default bilinear scaling — classic resampling, not AI.
Inflation Calculator
See what a dollar amount from any year between 1913 and 2025 is worth in another year using official US CPI data, or project a future value at a custom inflation rate.
Insulation R-Value Calculator — Assembly R-Value vs. Climate Zone
Stack as many insulation layers as your assembly actually has — material type and thickness per layer — and add them into a total R-value, then compare that total against published US DOE climate-zone recommendations for attics, walls and floors to see a plain meets/below-recommended verdict.
Intermittent Fasting Timer
Pick a 16:8, 18:6, 20:4, OMAD or 5:2 fasting protocol and watch a live countdown to your next eating or fasting window — a scheduling tool, not a health claim.
Invisible Text Generator
Copy invisible characters or generate blank text of any length: zero-width space, Hangul Filler, Braille blank and more.
Invoice Generator (PDF)
Fill in your business and client details, line items, tax rate and due date, then download a clean, correctly laid out PDF invoice — no signup and no cloud storage of your business data, unlike SaaS invoicing tools.
JSON / YAML / TOML / XML Serialization Converter
Bidirectional conversion between JSON, XML, YAML, and CSV config serialization formats fully client-side.
JSON to TypeScript Converter
Convert JSON into TypeScript interfaces, type aliases or a Zod schema live, with real optional-field detection across arrays.
JWK ⇄ PEM Key Converter
Convert cryptographic keys between JWK and PEM format using the real Web Crypto API, decode algorithm/curve/size, and compute the RFC 7638 JWK thumbprint.
Keyword Density Checker
Live keyword density analysis: top 1-, 2- and 3-word phrases with counts and density percentages, stop-word filtering and a target keyword check.
Kubernetes Manifest Linter
Lint Kubernetes YAML manifests against cluster-hardening best practices, entirely offline in your browser.
Length Converter
Convert length units instantly: millimeters, centimeters, meters, kilometers, inches, feet, yards and miles.
Life Path Number Calculator
Calculate your life path number from your date of birth and read what it says about you — privately in your browser.
Line Counter
Count lines in any text live as you type: total, non-empty and blank lines, plus longest and average line length.
Loan Calculator
Calculate the monthly payment, total cost and total interest of any loan, with a first-year amortization breakdown.
Long Division Calculator
Divide two whole numbers with the full long-division bracket drawn step by step: every multiply, subtract and bring-down, quotient with remainder, decimal expansion and mixed number.
Lucky Numbers Calculator
Get your personal set of lucky numbers derived from your birth date and, optionally, your name — with every source explained.
Macro Calculator (Protein, Carbs & Fat)
Calculate your daily protein, carbs and fat in grams from your calorie needs, goal and diet style — Mifflin-St Jeor based, right in your browser.
Magic 8-Ball
Ask a yes-or-no question and shake the classic Magic 8-Ball with its twenty original answers.
Margin Calculator
Calculate revenue, profit, margin and markup from a cost plus any one of selling price, margin percent or markup percent — with both formulas shown.
Markdown Converter
Instant two-way conversion between Markdown markup and plain HTML.
Markdown Table Generator
Build a Markdown table visually: click a cell and type, add rows and columns, set per-column alignment, and copy the ready GFM table.
Math Worksheet Generator
Generate a printable A4 arithmetic worksheet for kids — addition, subtraction, multiplication, division and number-house problems, plus a matching answer key.
Matrix Calculator
Add, subtract, multiply and transpose 2×2 or 3×3 matrices, plus find the determinant and inverse with the full cofactor-expansion trace — minors, signed cofactors, the adjugate and every step shown as exact fractions.
Meeting Time Planner
Compare one proposed meeting time across an organizer and two attendee time zones.
Meme Generator
Free online meme maker: caption your own images with classic top and bottom text and export PNG or JPEG.
Meta Robots & Canonical Builder
Build a valid meta robots tag and canonical link, or paste existing <head> HTML to audit it for real indexing conflicts like duplicate canonicals and contradictory directives.
Mic Test
Test your microphone online: live level meter, waveform and a record-and-playback check — fully in your browser.
Military Time Converter
Convert military (24-hour) time to regular 12-hour AM/PM time and back, with a full 24-row reference chart.
Minecraft Circle Generator
Generate pixel-perfect Minecraft circles and ellipses with thin, thick, or filled outlines and an exact block count.
Moon Phase Calculator
See the moon phase for any date: a drawn moon disc, illumination percentage, lunar age and the traditional meaning of the phase.
Mortgage Calculator
Calculate your monthly mortgage payment from the home price, down payment, rate and term — with property tax and insurance included.
Mulch, Topsoil, Compost & Gravel Calculator
Calculate how much mulch, topsoil, compost or gravel you need from area and depth — cubic yards, cubic feet, estimated weight and bags to buy.
Name Numerology Calculator
Turn a name into its numerology: expression, soul urge and personality numbers with interpretations — in your browser.
Net Present Value (NPV) Calculator
Discount a series of uneven cash flows back to today's value at a chosen rate, with a per-period discounted-value breakdown and a sensitivity table at nearby rates.
Never Have I Ever Generator
Deal family-friendly “Never have I ever” statements from friends, funny and travel decks — 90 hand-written cards with no repeats.
Number Base Converter
Convert numbers between binary, octal, decimal and hexadecimal — arbitrary size, entirely in your browser.
OG & Twitter Card Generator — Meta Tag Builder, Auditor & Preview
Build ready-to-paste Open Graph and Twitter Card <meta> tags from a form, or paste an existing <head> to audit it for missing tags, title/description length and twitter:card validity — then preview both in genuinely re-styled Twitter/X, Facebook, LinkedIn and Discord link-card mockups.
OG Image Generator — Social Share Image Maker
Compose a 1200×630 Open Graph social-share image with a title, subtitle, background and logo, rendered live on a real canvas — then preview how it looks framed inside Twitter/X, Facebook, LinkedIn and Discord link cards before you download the clean PNG.
Ovulation Calculator
Estimate your ovulation date, fertile days, and next period from your last period and cycle length.
Paint Calculator — How Much Paint for a Room or Wall
Work out how many liters of paint a room, wall, ceiling or facade needs: wall area from dimensions or direct input, minus doors and windows, times coats — with can sizes to buy.
Password Crack Time Estimator
Type a password and see a transparent entropy calculation plus honest crack-time estimates across several clearly-labeled attack scenarios — computed entirely in your browser, never a mystery strength score.
Password Hasher & Key Derivator
Hash passwords and derive cryptographic keys client-side using PBKDF2 and Scrypt KDF algorithms.
Payback Period Calculator
Find out how many years or periods it takes for an investment's cash flows to repay its initial cost, with simple and discounted payback compared side by side over a full cumulative cash-flow table.
PDF Form Filler
Open a fillable PDF, type your answers into a real form built from its own fields, and download a completed copy — entirely in your browser.
PDF Header & Footer / Page Number Stamper
Add page numbers ("Page X of Y") and/or custom header text to every page of a PDF, with adjustable position and a start-at offset, entirely offline.
PDF Page Organizer
See every page of a PDF as a thumbnail, then drag to reorder, delete with undo and rotate single pages — and save the result locally in the browser.
PDF Redactor
Draw black boxes over sensitive parts of a PDF that permanently destroy the text and image data underneath — real redaction, not a cosmetic overlay.
PDF to Markdown Converter
Extract a PDF's text as structured Markdown: real heading detection from font size, list detection from bullets and indent — not one flat wall of text.
PDF to Text Converter
Extract the plain text from a PDF's text layer in the browser, page by page, ready to copy or download.
PDF Watermark Stamper
Stamp a text watermark — CONFIDENTIAL, DRAFT or your own wording — across every page of a PDF, diagonal, tiled or in a corner, entirely offline.
Percentage Calculator
Calculate percentages in every direction: X% of a number, what percent X is of Y, percentage change, increase and decrease.
Permutations & Combinations Calculator (nPr, nCr)
Compute nPr (permutations) and nCr (combinations) from the same n and r, with the real factorial-cancellation working shown step by step in exact BigInt arithmetic.
Personal Year Number
Find your personal year, month and day numbers for any date and read the theme of your current cycle.
Pet Name Generator
Pick a species and a style and get eight pet name ideas per click — with click-to-copy and a favorites shortlist.
Phone Number Numerology
Check the numerology of a phone number: its core number, dominant digits and what they are said to attract.
Photo Filters
Apply grayscale, sepia, invert and pencil sketch effects to photos with an intensity slider — locally in your browser.
Photo in Circle
Create beautiful round avatars with frames and gradient backgrounds completely offline.
Pixel Art Converter
Turn any photo into genuine retro pixel art: a real box-filter downscale plus nearest-color quantization onto a real Game Boy, CGA, PICO-8 or NES-inspired palette, with optional Floyd-Steinberg dithering.
Poker Odds Calculator — Texas Hold'em Equity Math
A combinatorics tool that computes exact win/tie/lose probabilities for Texas Hold'em hands using a real 7-card hand evaluator and full board enumeration or Monte Carlo simulation.
Position Size Calculator
Enter your account size, risk per trade, entry price and stop-loss to get the exact position size that keeps your risk within your rule, plus an R-multiple profit table.
Preferred RC Filter Designer
Find practical E12, E24, or E96 resistor and capacitor pairs for a target RC filter cutoff.
Pregnancy Due Date Calculator
Estimate your due date from the last period, conception date, or IVF transfer, with week-by-week milestones.
Pressure Converter
Convert pressure units instantly: pascals, kilopascals, megapascals, bar, psi, atmospheres and millimeters of mercury.
Price per Unit Calculator
Compare 2–4 products by their real unit price: prices are normalized per 100 g, per kg, per litre, per ounce or per item, the cheapest one is highlighted and the rest show how many percent more they cost.
Primality Checker
Test whether a number is prime and see exactly why: real trial division up to √n for small and medium numbers, and a genuine Miller–Rabin walkthrough for cryptography-sized numbers.
Prime Factorization Tree
Factor any integer into its prime factors and see it rendered as the classic branching factor tree taught in school, plus the compact exponent form (360 = 2³ × 3² × 5).
Projectile Motion Calculator
Enter a launch speed and angle to get the real range, max height and time of flight of a projectile — the launch velocity is decomposed into vx and vy, every kinematics substitution is shown, and an actual trajectory chart is plotted from those same equations.
Protein Intake Calculator (Daily Range)
Get your daily protein target as an honest low-high range in grams, based on your body weight and activity goal — plus food equivalents, right in your browser.
PX to REM Converter
Convert px to rem, rem to px and px to em at any base font size, with a copy-ready CSS line and a live reference table.
Pythagoras Square (Psychomatrix)
Build your Pythagoras square from your date of birth: a 3×3 psychomatrix with an interpretation for every cell.
Pythagorean Theorem Calculator
Solve a² + b² = c² step by step: find the hypotenuse from two legs, find a missing leg, or test whether three sides form a right triangle — with exact simplified radicals like 5√2, a scaled diagram, area and perimeter.
Quadratic Equation Solver
Solve ax² + bx + c = 0 with the full quadratic formula worked out step by step: exact roots like (3 ± √5)/2 or −1 ± 2i, the discriminant, the vertex and the factored form.
Race Training Plan Generator
Build a safe week-by-week mileage progression for your next race from your current mileage, race distance and weeks to go, using the published 10% rule plus a step-back taper.
Random Team Generator
Paste a list of names and split it into fair random teams by team count or group size.
Ratio Calculator
Simplify ratios, solve proportions A : B = C : x, scale ratios by any factor and convert them to fractions, decimals and percentages — with every step shown.
Readability Checker
Score your text live with six classic readability formulas: Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau and ARI.
Receipt Generator (PDF)
Generate a simple sales or payment receipt as a downloadable PDF — business name, itemized list, tax, total and payment method — with a compact thermal-printer layout option, assembled entirely in your browser.
Recipe Scaler
Paste an ingredient list, set the original and the target number of servings, and get every quantity rescaled with kitchen-friendly rounding.
Regex Tester Online
Debug JavaScript regular expressions live: highlighted matches, capture groups, flags, and replacement preview.
Remove Duplicate Lines
Delete repeated lines from any list or text instantly and privately in your browser.
Remove Line Breaks
Clean unwanted line breaks and extra whitespace from pasted text instantly and privately in your browser.
Rent Affordability Calculator
See how much rent you can afford under three real published affordability rules side by side — the 30% rule, the 50/30/20 budget, and the landlord's 40x-rent screening rule — plus a reverse mode that turns a target rent into a required income.
Reverse Text
Flip text backwards instantly: reverse characters, words, or lines right in your browser.
Rhyme Finder
Find perfect and near/slant rhymes for any English word from a curated ~1,500-word phonetic dataset, organized by real matching sounds, not spelling.
Ring Size Converter
Convert ring sizes between the US, UK, EU/ISO and Japanese systems, or start from a measured diameter or circumference in millimetres.
RLC Q Calculator
Calculate resonance, Q factor, and bandwidth for series or parallel RLC circuits.
Robots.txt Tester
Paste a robots.txt file, pick a crawler — including GPTBot, ClaudeBot and Google-Extended — and instantly see whether it can fetch a given URL path, with the exact rule and line number that decided it.
ROI Calculator
Calculate the return on any investment: total ROI %, profit, annualized CAGR and the doubling time by the rule of 72 next to the exact answer.
Roman Numerals Converter
Convert numbers 1–3999 to Roman numerals and back, with a place-by-place breakdown and strict validation.
Roofing Shingle Calculator — Squares & Bundles from Pitch
Add up your roof's footprint sections, enter the pitch as rise per 12 inches of run, and get the real sloped roof area, plus the squares and bundles of shingles to buy after waste — using the actual trigonometric pitch factor roofers use, not a flat area estimate.
Rotate & Flip Image
Rotate pictures by 90° or 180° and flip them horizontally or vertically, all locally in your browser.
Rotate PDF Pages
Rotate PDF pages by 90, 180 or 270 degrees — all pages or a chosen range — locally in the browser.
Rune of the Day
Draw one of the 24 Elder Futhark runes as your rune of the day, with its glyph, name and meaning.
Running Pace Calculator
Calculate your running pace per km and per mile, finish time and km splits, or predict race times with the Riegel formula — right in your browser.
Salary Converter
Convert any pay amount between hourly, daily, weekly, biweekly, monthly and annual — based on your real hours per week and weeks per year.
Savings Goal Calculator
Plan a savings goal two ways: find the monthly deposit that reaches a target amount by a date, or how long a given monthly deposit will take, with interest.
Schema Markup Generator (JSON-LD)
Build valid JSON-LD structured data for FAQ, Article, Local Business, Product, Breadcrumb, Organization and Event pages — live, private, ready to paste.
Screen Resolution Checker
See your screen resolution, browser viewport size, device pixel ratio, color depth and orientation — updated live as you resize.
Secret Santa Generator
Draw fair Secret Santa gift assignments with optional exclusion pairs, then reveal them one at a time by passing the device around — no email, no server.
Security Headers Analyzer
Paste raw HTTP response headers from curl -I or DevTools' Network tab and get a graded security audit — a real Content-Security-Policy grammar parser plus HSTS, X-Frame-Options, cookie flags and more, entirely offline.
SERP Snippet Preview
See how your title tag and meta description will look in Google search results — live desktop and mobile snippet preview with character and pixel counters.
Shoe Size Converter
Convert shoe sizes between US, UK, EU, JP and foot length in cm for men, women and kids — with the full chart row for every match.
Sig Fig Calculator
Count the significant figures in any number with every digit classified by rule, or round a number to 1–15 significant figures with exact string-based math.
Sitemap.xml Validator — Real Protocol Compliance Checker
Paste or upload a sitemap.xml (or sitemap index) and validate it against the real sitemaps.org protocol: root element and namespace, absolute <loc> URLs, the documented 50,000-URL / 50MB limits, <lastmod>, <priority>, <changefreq> — plus a freshness histogram and duplicate-URL detection.
Sleep Calculator — Sleep Cycle Bedtime & Wake-up Times
Find the best time to go to bed or wake up based on 90-minute sleep cycles, with age-based sleep recommendations — right in your browser.
Slope Calculator
Find the slope between two points as an exact fraction, plus the y-intercept, slope-intercept and point-slope forms, distance with a simplified radical, midpoint and angle of incline — with steps.
Sort Lines
Sort the lines of any list or text alphabetically, naturally, by length, or shuffle them — privately in your browser.
Speaker Test
Test your speakers online: left / right channel tones, a 20–200 Hz bass sweep and pink noise — all generated in your browser.
Speed Converter
Convert speed units instantly: meters per second, km/h, mph, knots and feet per second.
Split PDF Online
Split a PDF into single pages or extract a page range into a new document, right in the browser.
SRI Hash Generator
Generate a Subresource Integrity hash for any JS or CSS file and get a ready-to-paste script or link tag.
Stair Calculator — Risers, Tread Depth & Blondel Comfort Check
Plan a staircase from total floor-to-floor rise: get the number of risers, the exact riser height, a tread depth from the real Blondel comfort formula (2 x riser + tread), and whether the total run fits your available space.
Standard Deviation Calculator
Paste your numbers and get the sample or population standard deviation, variance, mean, SEM and CV% — with the squared deviations shown step by step.
Startup Cost Calculator
Add your one-time and monthly recurring costs, set a runway in months and a contingency buffer, and see the total capital you need to launch and survive.
Step Sequencer
Program a 16-step drum beat with kick, snare, hi-hat, and clap, then export it as a real WAV file.
Steps to KM Calculator — Steps, Distance, Miles & Calories
Convert steps to kilometers and miles (or find out how many steps a distance takes), using your real stride length or one estimated from your height, plus an optional walking calorie estimate.
String Escaper — JSON, JS, SQL & Regex
Escape or unescape strings for JSON, JavaScript/TypeScript, SQL and regex — live, entirely in your browser.
Subnet Calculator
Calculate the network address, broadcast, subnet and wildcard masks, host range and usable host count for any IPv4 address and CIDR prefix.
Sudoku Generator
Generate a fresh, playable Sudoku puzzle with a real backtracking solver that verifies every puzzle has exactly one solution.
Table of Contents Generator
Paste Markdown or HTML and get a nested, clickable table of contents with real GitHub-style collision-safe anchor slugs, plus the original content with heading IDs injected.
Tarot Card of the Day — Free Online Tarot Reading
Draw one card from a fully illustrated 78-card tarot deck for an honest online tarot reading — upright or reversed, with a real meaning to reflect on, drawn locally with no account and no tracking.
Tarot Three-Card Spread — Free Online Past/Present/Future Reading
Deal a past-present-future tarot spread from a fully illustrated 78-card deck online — three distinct cards, upright or reversed, each with a real meaning, drawn locally with no account needed.
Temperature Converter
Convert temperatures between Celsius, Fahrenheit and Kelvin instantly with exact formulas.
Test Card Number Generator (Luhn-Valid, Sandbox Only)
Generate fake, Luhn-checksum-valid test card numbers from publicly documented sandbox BIN ranges (Visa, Mastercard, Amex, Discover) for QA and checkout-flow testing. Not real cards.
Text Cleaner
Strip HTML tags, smart quotes, weird dashes, emojis and invisible characters from any text — with per-category counters, privately in your browser.
Text Similarity Checker
Compare two texts with real n-gram Jaccard similarity and a word-level LCS overlap score, with the matching passages highlighted side by side.
Text Splitter & Joiner
Split delimiter-separated text into lines or join lines back into one string, privately in your browser.
Text to Handwriting Converter
Turn typed text into a realistic handwritten note on lined notebook paper, rendered locally in your browser.
Tile Calculator — How Many Tiles You Need
Work out how many tiles a floor, wall or laminate installation needs: enter a room's dimensions or its area directly, pick a common tile size or a custom one, add a waste allowance for cuts, and get a shopping list in tiles and boxes.
Time Unit Converter
Convert time units instantly: milliseconds, seconds, minutes, hours, days, weeks, average months and years, with a live hh:mm:ss readout.
Tip Calculator
Calculate the tip and total for any bill, and split both evenly between any number of people.
Tire Size Calculator — Diameter & Speedometer Error Comparison
Parse metric (225/45R17) or flotation (33x12.5R15) tire codes, get sidewall height, overall diameter, circumference and revolutions per mile/km, and compare two sizes with the resulting speedometer error.
Title Capitalization Tool (AP, APA, Chicago, MLA)
Capitalize headlines by real style-guide rules — AP, APA, Chicago and MLA — with correct handling of articles, prepositions, hyphens and colons.
TOTP Generator — Live 2FA Authenticator Code
Paste a Base32 TOTP secret and watch the real, live 6-digit authenticator code rotate every 30 seconds — entirely offline in your browser.
Triangle Calculator
Solve any triangle from three known values — SSS, SAS, ASA, AAS or SSA — and get every side, every angle, the area, the perimeter and the heights, with the law of sines and cosines steps written out and a scaled diagram.
Truth or Dare Generator
Family-friendly truth or dare generator with kids, party and couples decks — 90 hand-written cards that never repeat until the deck runs out.
Tweet Thread Splitter
Paste a long post and split it into a real X/Twitter thread using the actual weighted character-counting rules — every URL counts as a fixed 23 characters and astral-plane emoji count correctly — with smart paragraph/sentence/word boundaries and thread numbering that reserves its own space.
URL Parser & Query Inspector
Deconstruct complex URLs, manage deep queries, and decode URL parameters cleanly fully client-side.
User Agent Parser
Paste any user-agent string — from a server log, a support ticket, or curiosity — and decode its browser, OS, engine and device type instantly, including known bots like Googlebot.
Username Generator
Generate unique aesthetic, gamer, cute or cool usernames from curated word pairs — with separators, numbers, leetspeak and platform length caps.
UTM Link Builder
Build campaign URLs with utm_source, utm_medium and utm_campaign tags — live output, validation and clean encoding in your browser.
VAT Calculator
Add VAT to a net price or extract it from a gross price at any rate — net, VAT amount and gross in one click.
vCard Generator (VCF)
Create a vCard 3.0 contact file (.vcf) with a live preview and a QR code that adds the contact to any phone on scan — free, in your browser.
Vector Calculator
Compute the dot product, cross product, magnitude, unit vector and angle between two 2D or 3D vectors — with the term-by-term dot product expansion, the i/j/k determinant mnemonic, and exact simplified radicals like 5√2 shown at every step.
Video Frame Extractor
Extract still frames from a video at a fixed interval or a specific list of timestamps and download each one, right in your browser.
Video to GIF Converter
Turn MP4 or WebM clips into animated GIFs right in your browser — pick the segment, FPS and width, no upload needed.
VO2 Max Calculator
Estimate your VO2 max (cardiorespiratory fitness) from the Cooper 12-minute run or the Rockport 1-mile walk test, with a fitness-level category by age and sex.
Volume Converter
Convert volume units instantly: milliliters, liters, teaspoons, tablespoons, fluid ounces, cups, pints, quarts, gallons and cubic meters.
Waist-to-Hip Ratio Calculator
Calculate your Waist-to-Hip Ratio (WHR) from waist and hip circumference, with the WHO 2008 risk category and a separate NIH/ATP-III waist-circumference cross-check.
Wallpaper Calculator — Rolls Needed, Pattern-Repeat Waste Included
Work out how many wallpaper rolls a room needs: enter the wall length (or room length × width) and height, pick a roll size, and — unlike a flat waste percentage — enter the pattern repeat so the calculator can show the real material lost to matching a large repeat.
Water Intake Calculator
Estimate how much water you should drink a day from your weight, exercise and climate — in liters, milliliters and 250 ml glasses, right in your browser.
Web App Manifest Validator
Validate a PWA manifest.json against the Web App Manifest spec and preview maskable icons against Android's adaptive-icon safe zone.
Wedding Date Calculator
Rank the numerologically favorable wedding dates in any range, personalized by both partners' birth dates.
Wheatstone Bridge Calculator
Calculate Wheatstone bridge differential output, balance point, and excitation-relative error.
Word Frequency Counter
Count how often every word appears in your text and get a ranked frequency table, privately in your browser.
Word Search Generator
Turn any word list into a printable word search puzzle using a real backtracking placement algorithm, with a matching solution key.
Work Hours Calculator
Add up a full week of clock-in and clock-out times with breaks, overtime split, and optional gross pay.
Would You Rather Generator
Deal random would-you-rather dilemmas from three decks — kids, funny and hard — pick a side and watch your session stats.
Z-Score & Confidence Interval Calculator
Compute a z-score for a value against a normal distribution, or a confidence interval for a sample mean — with the standardization formula and the exact critical z-value substituted step by step.
ZIP Extractor — Open ZIP Files Online
Open any ZIP archive in your browser: browse the full file tree with sizes and download only the files you need — nothing is uploaded.
Zodiac Sign Calculator
Find the zodiac sign for any birth date with its element, quality, ruling planet and best matches.
What this site is
Invistools is a library of more than 400 small, single-purpose tools. Each one does exactly one job — resize an image, split a PDF, format JSON, tune a guitar, work out a resistor value, count the days between two dates — and does it on the page you open, with no installation and no setup step. The catalogue is sorted into eleven categories: text, images, PDF and documents, audio, music, electronics, time and dates, everyday utilities, validators, esoteric and games.
How "runs in your browser" actually works
A tool page is a small program your browser downloads once and then executes on your own machine. When you pick a file, the browser hands it to that program through ordinary web APIs — FileReader for raw bytes, Canvas for images, Web Audio for sound, WebAssembly for the heavier formats — and the result is written straight back into the page you are looking at. No step in that chain involves a server: there is no upload endpoint waiting to receive your file and no queue on the other side to process it. It is also why a tool keeps working if your connection drops after the page has loaded.
Why that matters
Because nothing is transmitted, nothing can be stored, inspected or leaked later. That is not a claim about how carefully we handle your data — it is a consequence of where the code runs. You do not have to take it on faith either: open your browser's developer tools, switch to the network panel, run any tool on a real file, and watch that your document never shows up in a request.
No accounts, no quotas, no watermarks
There is no registration, no login and no paid tier holding back the real version. Nothing is metered — you can run the same tool a hundred times in a row, on files as large as your browser can hold in memory — and nothing is stamped onto the output. Because no account exists, there is no profile and no file history that could go missing. The only things the site remembers are your interface language and the tools you starred as favourites, and both stay in your browser's local storage.
Who runs Invistools
Invistools is built and maintained by Invis Matters, an independent studio that develops and runs its own products. Invistools is one of them, funded by the studio itself rather than commissioned by a client. The About page has the longer version, and the contact page carries a working address that reaches the studio directly.
How it is paid for
Hosting, domains and the hours behind each tool cost money, and advertising on the pages plus voluntary donations cover it. The tools stay free and complete either way — nothing is held back behind a payment, and your files are never part of the transaction.
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