Small tools that run entirely in your browser
This is a collection of single-purpose utilities for developers, designers, students and anyone who occasionally needs a precise answer to a fiddly question — or just needs to check that a piece of hardware works. What does this cron expression do, what changed between these two files, does this colour pair pass WCAG, is my microphone actually picking anything up, what do I need on the final. Each one is a plain static page that loads in a moment, does its job, and never asks you to sign up for anything.
Developer & design tools
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JSON Formatter & Validator
Format, validate, minify and explore JSON in a collapsible tree. Invalid input gets the exact line and column with a caret under the character that broke it, not just “unexpected token”. Nothing you paste is uploaded — it is parsed in your browser.
Open the JSON formatter -
Cron Expression Generator
Build a cron expression from dropdowns, or paste one in and get a plain-English explanation plus the next five times it will actually fire. Includes a preset library and ten pages covering the schedules people search for most.
Open the cron generator -
Aspect Ratio Calculator
Give it any two of ratio, width and height and it solves for the third, with presets for 16:9, 4:3, 21:9, 9:16 and 1:1 and the nearest standard resolution. Platform pages cover YouTube, Instagram, TikTok and 4K.
Open the ratio calculator -
Unix Timestamp Converter
Timestamp to date and date back to timestamp, auto-detecting whether you pasted seconds or milliseconds. There is a live clock, the full IANA timezone list, and a batch mode for converting a whole column at once.
Open the timestamp converter -
Days Until
Count the days between two dates, or start a live countdown to one. Twelve event pages work out their own next occurrence when the page loads, so a countdown to Christmas or Halloween is never pointing at a date that has already passed.
Open the countdown calculator -
WCAG Contrast Checker
Enter a foreground and background colour and get the exact contrast ratio, with AA and AAA verdicts for both normal and large text. When a pair fails, it suggests the nearest colour in the same hue that would pass.
Open the contrast checker -
Regex Cookbook & Tester
Copy-paste patterns for email, URL, phone, IPv4, ISO dates, slugs, hex colours and UUIDs, each with a plain-English explanation. Paste your own pattern against sample text for live match highlighting, capture groups and a replace preview.
Open the regex cookbook -
SMPTE Timecode Converter
Convert timecode to frames, frames to timecode, and either to real running time, at every broadcast rate from 23.976 to 60. Handles drop-frame properly — including why 29.97 non-drop drifts 3.6 seconds an hour, and which frame numbers do not exist.
Open the timecode converter -
Prometheus Cardinality & Storage Estimator
Work out how many active time series your labels actually produce, and how much disk that needs over a retention window. Shows every step, and flags the label that turns a harmless metric into millions of series.
Open the cardinality estimator -
Diff Checker & Text Compare
Paste two blocks of text and see exactly what changed, line by line — added, removed and unchanged — with options to ignore case, whitespace or blank lines. The comparison runs in your browser; nothing you paste is uploaded.
Open the diff checker -
CSS Gradient Generator
Build linear, radial and conic CSS gradients visually — colour stops, angle and shape — with a live preview and the exact background: declaration to copy.
Open the gradient generator -
CSS Box-Shadow Generator
Design a CSS box-shadow with offset, blur, spread, colour and inset — stack multiple layers — and copy the exact declaration, with a live preview and presets.
Open the box-shadow generator -
JWT Decoder
Paste a JSON Web Token and see the decoded header and payload as colour-coded JSON, with an expiry badge. Decoded entirely in your browser — never verified against a key, never uploaded.
Open the JWT decoder
Device, hardware & sound
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Mic Test
Check your microphone in the browser with a live input level meter and a device picker, plus readouts for sample rate and channels. The audio never leaves your device — nothing is recorded or uploaded.
Open the mic test -
Webcam Test
A live camera preview with the actual resolution, frame rate and device stats, resolution presets and a mirror toggle. The video feed stays on your device — a snapshot, if you take one, is saved locally.
Open the webcam test -
Keyboard Tester
Press any key to see it light up on a full ANSI or ISO board, watch which keys you have tested, and check how many keys register at once to spot ghosting and rollover limits. Reads live key, code and keyCode values.
Open the keyboard tester -
Monitor & Dead Pixel Test
Fullscreen colour patterns and a stuck-pixel flasher to check a screen for dead pixels, stuck pixels, backlight bleed and colour uniformity — with the difference between a dead and a stuck pixel explained.
Open the monitor test -
Tone Generator
Play any frequency from 20 Hz to 20 kHz in four waveforms, with the nearest musical note and cents offset shown live — for tuning, testing speakers and headphones, or sound design.
Open the tone generator -
Hearing Test
Step through tones from 8 kHz to 20 kHz to find the highest frequency you can still hear. A quick, non-medical check of your high-frequency range — best with headphones.
Open the hearing test -
Gamepad Tester
Test every button, trigger, stick and D-pad on a connected controller live, watch for stick drift and deadzone, and fire a rumble test — all in your browser, no install.
Open the gamepad tester -
Mouse Tester
Check every mouse button and the scroll wheel, catch double-click chatter on a worn switch, and read an approximate polling rate — handy before you return a faulty mouse.
Open the mouse tester -
Virtual Piano
Play a two-octave piano with your mouse, touch or computer keyboard — correct pitches, real chords, octave shift and sustain, synthesized live with the Web Audio API.
Open the virtual piano -
Guitar Tuner
A chromatic microphone tuner with a live frequency, note name and a cents-off needle, plus Standard, Drop D, Half-step, Open G and DADGAD presets. The audio stays on your device.
Open the guitar tuner
Speed, skill & study tools
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Reaction Time Test
Click, tap or press Space the instant the screen turns green, and get your reaction time in milliseconds over a five-attempt run, with your best and mean and an all-time best kept on your device.
Open the reaction time test -
CPS Test — Clicks Per Second
Measure how fast you can click over rounds from one to a hundred seconds, with a live count and clicks-per-second and a best score saved per duration. A right-click variant is a click away.
Open the CPS test -
Spacebar Counter
Count spacebar presses free-form, or run a timed speed test from five to sixty seconds scored in presses per second. Auto-repeat is filtered out, so held keys never inflate the count.
Open the spacebar counter -
Grade Calculator
Work out a weighted average grade with a letter-grade readout, then solve the other question that matters at exam time: exactly what score you need on the final to reach the grade you want.
Open the grade calculator -
GPA Calculator
Compute weighted and unweighted GPA on the standard 4.0 scale from your letter grades and credit hours, and combine a prior cumulative GPA with a new term to see where you land.
Open the GPA calculator
Gaming tools
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Mouse Sensitivity Converter
Convert your mouse sensitivity between FPS games using each game's yaw constant, and get your eDPI, cm/360 and in/360 so your aim feels the same everywhere.
Open the sensitivity converter -
Aim Trainer
Flick and grid target-clicking practice with live accuracy, targets-per-second and time-to-hit, timed rounds, and a saved best score. A quick warm-up before you queue.
Open the aim trainer -
Pixel Circle Generator
Turn a diameter — or a width × height — into a blocky circle or oval template with exact block counts, for building round shapes in Minecraft and other voxel games.
Open the pixel circle generator
Text, generators & pickers
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Case Converter
Paste text and get it in every case at once — UPPERCASE, lowercase, Title Case, camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE and more — each with its own copy button.
Open the case converter -
Remove Line Breaks
Clean up text pasted from a PDF or email: join wrapped lines, collapse runs of spaces, trim each line and drop empty lines — with an option that keeps real paragraph breaks intact.
Open the cleaner -
Text Repeater
Repeat any text a set number of times with your choice of separator, optional numbering and a trailing separator — with a length cap so a big number never freezes the tab.
Open the text repeater -
Lorem Ipsum Generator
Generate placeholder text by paragraphs, sentences or words, with the classic “Lorem ipsum dolor sit amet” opening and a copyable plain-text or HTML-wrapped output.
Open the lorem ipsum generator -
UUID Generator
Generate v4 (random) or v7 (time-ordered) UUIDs in bulk using your browser’s own crypto, with uppercase, hyphen and quoting options, and an inspector that reads a UUID’s version.
Open the UUID generator -
Wheel Spinner
Type in a list of names or options, spin an animated wheel, and get a fair, uniformly random pick — for classrooms, giveaways, decisions or streams. Includes a yes/no wheel.
Open the wheel spinner -
Random Team Generator
Paste a list of names and split them into shuffled, balanced teams — by number of teams or by team size — with the remainder spread evenly rather than dumped on the last team.
Open the team generator -
Tier List Maker
Sort text or image tiles into S-to-F rows by click, tap or keyboard, rename and recolour the tiers, then export the finished board as a PNG. Your layout is saved in your browser.
Open the tier list maker -
Would You Rather
Tap for a random would-you-rather dilemma from a family-friendly bank of 128, filter by category, and keep a local tally of which side you pick. Good for road trips and classrooms.
Open would you rather -
Truth or Dare
Truth or Dare and Never Have I Ever in one generator, with a category filter and no repeats. Every prompt is kept family-and-classroom-friendly on purpose.
Open truth or dare -
Band Name Generator
Random band-name ideas across ten genre flavours and five name patterns, with an optional word of your own mixed in. Generate a batch and copy your favourite.
Open the band name generator -
Username Generator
Generate gamertag and handle ideas from a keyword and a style, with numbers, separators and length under your control. Ideas only — it can't check availability.
Open the username generator -
Bingo Card Generator
Generate unique printable bingo cards — 75-ball, 90-ball, or your own word list — with a free-space option, then print them or save as a PDF from your browser.
Open the bingo card generator
Fancy text & symbols
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Fancy Text Generator
Type once and get your text in 20 decorative Unicode styles — bold, italic, cursive script, gothic, double-struck, bubble, small caps and more — each with a copy button.
Open the fancy text generator -
Discord Font Generator
Turn your text into Unicode fonts that paste into Discord nicknames, server and channel names and bios — with honest notes on what works where and a markdown formatting helper.
Open the Discord font generator -
Invisible Character
Copy blank and invisible Unicode characters — with their codepoints and honest per-platform notes — or generate a batch of them for an empty message or username.
Open the invisible character tool -
Symbol & Emoji Copy-Paste
A categorised, searchable grid of hearts, arrows, stars, currency, math signs, punctuation, kaomoji and check marks. Click any symbol to copy it — no Alt-codes to memorise.
Open the symbol hub -
Zalgo / Cursed Text
Turn plain text into glitchy “cursed” text by stacking Unicode combining marks, with an adjustable intensity and a button to strip the marks back off.
Open the zalgo generator
Word games
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Word Unscrambler
Enter your letters — with wildcards for blank tiles — and instantly find every word you can make, grouped by length. Built on a large English word list, all in your browser.
Open the word unscrambler -
Anagram Solver
Find every exact anagram of your letters, or every shorter word hidden inside them, grouped by length — for puzzles, pen names and word games.
Open the anagram solver -
Wordle Solver
Mark your green, yellow and grey clues and instantly filter the five-letter words that still fit, with a suggested next guess. A helper, not the day's answer.
Open the Wordle solver -
Tile Word Finder
Find every playable word from your tile rack, ranked by score, with blank-tile support and both classic and mobile scoring systems, plus board-hook filters.
Open the word finder
Image tools
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Image Compressor
Shrink JPEG, PNG and WebP images by quality or by dimensions, with a before-and-after size comparison. The image is decoded and re-encoded in your browser and never uploaded.
Open the image compressor -
Image Resizer
Resize an image to an exact width and height or a percentage, with an aspect-ratio lock, and export as PNG, JPEG or WebP. Everything happens in your browser — nothing is uploaded.
Open the image resizer -
Favicon Generator
Drop in one image and get every favicon size plus a real multi-resolution favicon.ico and a ready-to-paste link snippet — all built in your browser, with no upload.
Open the favicon generator -
EXIF Viewer & Remover
Read a photo's camera and GPS metadata, then strip it and download a clean copy before you post. The image is decoded and re-encoded in your browser — nothing is uploaded.
Open the EXIF viewer
Media & recording
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Teleprompter
Paste a script and read it to camera with a smooth, adjustable scroll, a mirror mode for beam-splitter rigs, a countdown and fullscreen — plus optional local recording. Nothing is uploaded.
Open the teleprompter -
Screen Recorder
Record your screen, a window or a browser tab with optional microphone audio, then download the video — right in your browser, no install, no sign-up, and nothing uploaded.
Open the screen recorder
What makes these different
Most online utilities of this kind are a thin layer of arithmetic wrapped in several megabytes of framework, and they send everything you type to a server to get an answer back. These are built the other way round: the tool is the whole page, and the answer is worked out where you are standing. The points below are structural, not promises — they are what the pages are made of, and you can check them yourself in a minute: open your browser’s Network tab and type into any tool here. Your input never produces a request.
- Everything is computed on your device The maths runs in your browser in JavaScript. The colours, timestamps, dates and cron expressions you type are never transmitted anywhere, because there is nowhere for them to be transmitted to — these tools have no server component at all.
- What you type is never collected Nothing you enter is uploaded, logged or stored. Not the production cron expression, not the internal timestamp, not the brand colours. Your input goes in, the answer comes out, and nobody else ever sees either.
- Answers are instant There is no server round-trip to wait for. The result updates as you type, because the calculation is happening a few centimetres from your fingertips.
- No account, nothing to install No sign-up, no login, no extension, no download. A few tools keep a small setting or a personal best in your browser’s own local storage — the timestamp converter’s timezone, the countdown’s date order, a best reaction time or click-speed score. Each one stays on your device, contains no identifier, and clearing site data removes it.
- The tools keep working offline Once the page has loaded, each tool needs nothing but itself. Lose your connection and it keeps working — and it works just as well saved to disk and opened as a file.
- No build step, no dependencies Hand-written HTML, CSS and vanilla JavaScript with no framework and no package manager. Nothing here can break because a dependency three levels down changed.
To be plain about the limits of that: the server hosting these pages still sees an ordinary web request when you load one, the same as any website, and the host keeps its own operational logs. Advertising or analytics may be added later to cover hosting, and if that happens the privacy policy will be updated to say exactly what was added before it goes live. What will not change is that your inputs stay in your browser.
More about this collection
- About these tools Why the collection exists, how it is built, and who it is for.
- Contact Corrections, bug reports and suggestions — by email, no form.
- Privacy What is and is not collected, stated plainly.