The whole toolbox at a glance — converters, calculators, colour checkers and generators that run entirely in your browser.
Length, weight, volume, area, speed, temperature, time and digital storage — exact factors, every unit at once, nothing uploaded.
Days between any two dates, add or subtract days, exact age in years-months-days, working days and days to your next birthday.
WCAG contrast ratio between any two colours with AA/AAA verdicts, the nearest accessible colour, and tints & shades palettes.
True random passwords from your browser’s cryptographic generator, with honest entropy maths — the password never touches our server.
Word counter, case converters (camelCase, snake_case, kebab…), URL & Base64 encoders and SHA-256 hashing — all offline, all instant.
BMI with WHO bands, your healthy weight range for height, BMR and daily calorie needs (Mifflin-St Jeor) plus body-fat and waist-to-height estimates.
Shrink a photo or screenshot right in your browser — resize, pick quality, compare before/after and download. Your file never uploads anywhere.
Look up any word’s meaning and translate it across dozens of human languages — plus ancient scripts and playful animal, alien and sound “languages”, with spoken pronunciation.
What is X% of Y, X is what percent of Y, percent change and add-or-subtract a percentage — with the arithmetic printed beside every answer.
Monthly loan payments, total interest, the effect of extra payments, and compound savings growth — the maths printed honestly, no quote requested.
Turn a link, text or Wi-Fi network into a QR code in your own browser, with error-correction controls and a print-ready PNG download.
Your public address, the ISP-level location databases infer from it, and every browser field a website can read — shown openly, nothing stored.
Epoch to date and back, with seconds/millisecond auto-detection, ISO 8601, your local zone and a live ticking clock.
Unbiased integers, d4–d100 dice and a raffle-style list picker — drawn from crypto.getRandomValues with rejection sampling, so nothing is favoured.
Merge, extract, delete, rotate and split PDF pages without uploading the file — the document is opened and re-saved by your own browser.
Format, minify and validate JSON with the exact line and column of a syntax error; large numbers and key order survive because it scans instead of re-parsing.
MD5, SHA-1, SHA-256, SHA-384 and SHA-512 of text or a whole file at once — verify a download against its published checksum privately.
UTF-8-correct Base64 both ways, URL-safe output, and a file turned into a data: URL — with the honest note that encoding is not encryption.
Compare up to eight cities hour by hour and find the call time that works for everyone — real IANA offsets and daylight saving, computed in the browser.
Random v4 and time-ordered v7 identifiers in bulk, plus a decoder that shows the version, variant and any embedded timestamp.
Any five-field cron schedule in plain English with its next ten runs, every field validated — including the day-of-month/day-of-week OR trap.
Test JavaScript regular expressions with live match highlighting, group inspection, and a common-pattern library (email, URL, IPv4, dates).
Paste CSV or TSV and see it as a formatted table instantly. Convert to JSON, copy or download — RFC 4180 compliant, all local.
Compare two blocks of text line-by-line or word-by-word: additions, deletions and unchanged parts highlighted instantly.
Break a URL into protocol, host, port, path, query parameters and fragment. Encode and decode components side-by-side.
Inspect any character: Unicode code point, HTML entity, UTF-8 bytes and UTF-16 unit count — a quick-reference for invisible bugs.
A live on-screen compass from your device’s magnetometer, plus the true-north bearing and great-circle distance to 46 world cities (a qibla pointer, the way home, the next town).
Convert between PNG, JPEG, WebP, BMP and ICO, and rasterise an SVG — resize, pick a quality, keep or replace transparency, download. The file never leaves your browser.
Put photos, scans or screenshots into one PDF — A4, US Letter or a page sized to each image — without uploading. JPEG and PNG files are embedded byte-for-byte, untouched.
Any whole number in base 2, 8, 10, 16 — or any base from 2 to 36 — computed exactly with BigInt, even numbers a desktop calculator overflows.
Text to UTF-8 bytes as 01101001 and back again, in binary, hex, octal or decimal — the honest way to see what a string really is.
Is it prime? A deterministic Miller–Rabin answer for numbers up to 2⁶³, plus the full prime factorisation when it is not.
Fractions that show their working: exact + − × ÷ with lowest terms by the Euclidean algorithm and the mixed-number form.
The full descriptive summary of any list of numbers — mean to quartiles — with the sample-vs-population choice made visible, not hidden.
Hourly to annual and back with your real schedule (hours per week, weeks per year), plus the 1.5× overtime figure — gross maths, no tax claims.
The restaurant napkin maths: tip, total and each person's share, with a round-up option so the payment is exact down to the coin.
Sale price from any percent off, a second coupon applied honestly on the remainder — and the equivalent single discount exposed.
A live seconds-accurate countdown to any date — exams, flights, launches, birthdays — that keeps counting up after it passes.
What you need on the final for the grade you want — or a straight "it is mathematically impossible" with the best achievable score.
Encode text so it survives an HTML parser and decode entity soup back, using the browser's own decoding table — nothing sent anywhere.
Read any JWT's header and claims with expiry dates made human — and an honest refusal to pretend an unsigned token is verified.
Numbers to Roman and back with the real canonical rules — the page tells you IIII is a clock, not a document.
Any number spelled out — including the cheque form banks actually ask for — exact up to 24 digits because it runs on integers, not floats.
A raw span of seconds read the way people say it — 2d 8h 16m 40s — and back, refusing to pretend a month has a fixed length.
Does this card/IBAN/ISBN/barcode pass its own check digit? The published algorithm, the working printed, and the honest limit: validity is not ownership.
The 500 g vs 1 kg decision settled by price per unit, with the percentage gap and what the other pack would cost at the winner’s rate.
The pump-and-odometer maths both traditions ask for — L/100 km and km/L and US MPG — plus what the trip actually cost.
The napkin maths of sleep: count back in 90-minute cycles from your alarm and see which bedtimes wake you mid-cycle-free.
Proper placeholder text — scrambled from the real De Finibus word bank, variable sentence lengths, no “asdfgh” filler.
Turn 1920×1080 into 16:9, check what a crop actually is, and resize to fit any box with the rounding error printed.
px to rem to pt with your real root font size, and an honest note about the one unit (em) that depends on context this page cannot see.
The true 2d6 curve computed as exact counts — 21 of 36 outcomes are 7 or better — with the full distribution as a table.
The two-minute question answered twice: theoretical minimum and the 85%-of-line-rate figure ISPs actually let you have.
C(52,5) = 2,598,960 poker hands as an exact integer — combinations, permutations and factorials with no float ever touching the maths.
gcd(1071,462) = 21 with each Euclidean division printed as it happens — plus the LCM, the coprime verdict and the reduced fraction.
Three sides in, three angles, area and perimeter out — with the triangle inequality and the right/obtuse verdict stated honestly.
Flesch Reading Ease and Kincaid grade for any English text, with the syllable maths and a 230-wpm reading time — computed on your device.
BMR and daily calorie needs via Mifflin-St Jeor — the formula dietitians actually validate against — with weight-change rows instead of promises.
Prices forward and values backward by compound maths — with the exact doubling year count next to the rule-of-72 shortcut.
The ciphers history actually used — Caesar, ROT13, Atbash, Vigenère — encoded and decoded with the shift maths printed and no false security claims.
How much paint the room actually needs: wall area minus doors and windows, at the tin's real m²-per-litre, with waste and second coats included.
Halve, double or 2.5× a recipe and read the result as fractions a human measures with — ¾ tsp, not 0.75 tsp.
3000×2000 prints 10×6.7 inches at 300 dpi — plus the honest physics of how big you can actually go before the dots show.
The real money an appliance burns: watts-hours to kWh, your own tariff, the annual figure, and what that always-on standby light actually costs.
Pace per km and mile, even splits from 5K to marathon, and the Riegel 1.06 prediction with its honest warning about the wall.
The poster maker without the login wall: backgrounds, text, shapes and images as real layers, exported as PNG straight from your canvas.
How much water is actually enough for your weight, your training week and your climate — converted into glasses, bottles and an hourly sip pace you can follow.
A lump sum and a monthly habit grown year by year with true compounding maths — including the effective annual rate banks quote differently and the exact doubling time, not just rule of 72.
Add GST/SST/VAT to a price or strip it back out of a receipt — with the exact net and tax split, and every common world rate compared on the same number.
Follow a growing and shrinking circle through coherent, box and 4-7-8 breathing — the visual pacer that makes a one-minute calm session actually work.
Text to International Morse and back with the full ITU table including punctuation, word-gap slashes, and dit/dah playback generated by your browser's own audio oscillator.
Read any code out loud unambiguously: the official ICAO words Alpha through Zulu plus the digit list, both directions, with the awkward-pronunciation notes.
The week number the standard actually defines — first week contains a Thursday, weeks start Monday — plus day-of-year, days left, and the reverse lookup from W-number to dates.
A Markdown-to-HTML converter that escapes angle brackets before it formats, so no script tag ever survives the trip — paste, copy, done, nothing uploaded.
Paste any identifier — getUserID, http-request, API_KEY_2 — and get all nine naming conventions from one tokenisation, camelCase humps included.
How far is it really between two lat/lon dots: haversine great-circle distance in km, miles and nautical miles, with the compass bearing you would leave on.
A printable month grid for any month in 240 years — Monday or Sunday start, ISO week numbers down the side, generated from calendar arithmetic and nothing else.
Sixty seconds, sixty common words, live scoring by the standard typing-test convention — 5 keystrokes = 1 word, errors count against you, nothing leaves the page.
Drop in your courses, credits and letters — get the credits-weighted GPA with the arithmetic visible, your degree-class band, and what it takes to hit a target.
Foot length in centimetres to EU, UK and US sizes and back — the real formulas (Paris point, Brannock barleycorns) instead of a table you cannot check.
Put any two screens side by side and get real width, height and pixel density — plus the area comparison a diagonal-inches number is designed to hide.
A precise click track from the browser\u2019s own audio clock — 40 to 208 BPM, accented first beat, 2/3/4/6 per bar, and the Andante-to-Presto names the sheet music promises.
A lap-split stopwatch whose time comes from the system clock, not a ticking counter — background-tab throttling cannot make it drift a single millisecond.
The ABO cross done honestly as a Punnett square — pick both parents\u2019 genotypes and see why two group-A parents can have an O child, with every odds percentage.
Complement, reverse complement, mRNA and the actual protein from the standard codon table — the four readings every genetics course asks for, computed on your device.
The full IPv4 breakdown of any CIDR — network, broadcast, first and last usable address, mask and wildcard, and the next block in the allocation, by pure arithmetic.
Training zones computed the way exercise science does — heart-rate reserve from your <i>resting</i> rate, not raw percentages of a mythic 220-minus-age max.
Track the exponential decay of your last coffee hour by hour — when the body load drops below 100 mg, and how much is still circulating when you plan to sleep.
The Moon\u2019s age, phase name and lit fraction for any date from the mean synodic month — with the ±1 day accuracy honestly stated.
Easter Sunday for any year from the 6th-century algorithm the Church still uses — Western and Orthodox dates side by side, with the intermediate golden number and epact.
What weekday is 14 March 2027? A calendar-correct answer for any date, plus every year your birthday lands on a Saturday.
How many days until the deadline — plain, or weekends excluded, with the ISO week span and the y-m-d breakdown.
The same file in decimal and binary units with the exact byte count — why 500 MB is 476.8 MiB, and why 100 Mbps is 12.5 MB/s.
Entropy bits instead of a coloured bar: the character pool, the dictionary and-pattern penalties, and what a GPU cracking rig needs.
See the infinite inside a fraction: the long-division expansion with the repeating cycle marked, its length, and the remainder trail that proves it must repeat.
Press every key and see every register — the two-minute health check for a secondhand laptop, a borrowed keyboard or a suspect switch.
Run proper pomodoro sessions — 25 minutes of work, 5 of rest, a long break every fourth — with the countdown kept on the system clock, so a throttled tab loses nothing.
Count a text the way a word processor does and quote the reading time that matches the claim — average silent reading, reading aloud, or a recorded narration, all from research speeds.
Generate real EAN-13 barcodes from 12 digits — the check digit computed with the official 1,3 weights and the bars drawn straight onto a canvas, with the encoding table on the page.
Crème Brûlée becomes creme-brulee — accents stripped properly, symbols spelled out before they are dropped, and the length cut never leaves a dangling dash.
Tukuk-OS