100+ free tools that run entirely in your browser. No upload, no sign-up, no tracking.
Popular tools
Free tools that run in your browser
More than 100 calculators, converters and everyday utilities. No account, no upload, no queue — everything is computed in the page, so nothing you paste is sent anywhere.
Debug an error, build a regex and watch it match your own samples, turn plain English into SQL on your schema, generate unit tests, pre-review code, untangle someone else’s code. Free, no sign-up, results stay in your browser.
Repair scratches and fading in family photographs, sharpen and colorize, or turn one casual photo into a professional headshot, anime, 3D or watercolor avatar. The features people pay dedicated apps for — free here, and your photo is never stored.
Developer tools
JSON Formatter
Pretty-print messy JSON, or compress it to a single line.
Open the toolJSON Validator
Find the exact line and character where JSON stops parsing.
Open the toolJSON Viewer
Walk a large document as a collapsible tree instead of a wall of text.
Open the toolJWT Decoder
Read a token header and payload, with the expiry shown as a real date.
Open the toolBase64 Encoder
Encode text or a file to Base64, in standard or URL-safe alphabet.
Open the toolBase64 Decoder
Turn Base64 back into readable text without guessing the variant.
Open the toolURL Encoder
Percent-encode a URL or query value, with the ampersand trap handled.
Open the toolURL Decoder
Decode percent-encoded links, including the double-encoded ones.
Open the toolUUID Generator
Generate v4 and time-ordered v7 identifiers in bulk, not one at a time.
Open the toolTimestamp Converter
Convert Unix time in seconds or milliseconds to a date, and back.
Open the toolJSON Minifier
Strip the whitespace out of JSON before it ships.
Open the toolRegex Tester
Test JavaScript regex with live match highlighting and captured groups.
Open the toolHash Generator
Compute SHA-1, SHA-256, SHA-384 or SHA-512 digests in the browser.
Open the toolBase Converter
Convert between binary, octal, decimal, hex and Base64.
Open the toolRoman Numeral Converter
Turn numbers into Roman numerals and back, as you type.
Open the toolCode Formatter and Minifier
Beautify or minify HTML, CSS and JavaScript with js-beautify and Terser.
Open the toolCSV to JSON Converter
Convert CSV to a JSON array and back, with quoted-field support.
Open the toolImage to Base64
Encode an image as a data URL or preview one, all in the browser.
Open the toolHTML to Markdown
Convert common HTML to Markdown for headings, lists, links and code.
Open the toolFind and Replace
Find and replace across text, with a case-sensitive option.
Open the toolYAML to JSON Converter
Convert YAML to JSON and back, with js-yaml in your browser.
Open the toolHTML Entities Encoder
Encode text into HTML entities or decode entities back to characters.
Open the toolText to Binary / Hex
Convert text to binary or hex, or decode binary and hex back to text.
Open the toolJSON to TypeScript
Turn JSON into TypeScript interfaces — nested objects and arrays handled.
Open the toolCalculators and converters
Unit Converter
Settle metric against imperial for length, weight, volume and heat.
Open the toolLoan Calculator
Monthly payment, total interest, and what two extra years really cost.
Open the toolCompound Interest
Watch a balance grow with contributions, year by year.
Open the toolBMI Calculator
Body mass index in metric or imperial, with the healthy range.
Open the toolAge Calculator
An exact age in years, months and days between any two dates.
Open the toolTip & Split
Work out the tip and what each person owes.
Open the toolCurrency Converter
Convert between currencies at the current rate.
Open the toolTime Zone Converter
Compare a meeting time across cities and offsets.
Open the toolScientific Calculator
Trigonometry, logs, powers and constants, with a history.
Open the toolGPA Calculator
Weighted grade point average from grades and credit hours.
Open the toolRandom Numbers
Random draws in any range, with optional no repeats.
Open the toolCountdown Timer
Days, hours and minutes until a date you pick.
Open the toolPassword Generator
Create strong, random passwords with custom length and character sets — instantly, in your browser.
Open the toolAspect Ratio Calculator
Simplify a width and height ratio and scale one dimension to another.
Open the toolDate Calculator
Days between two dates, or add and subtract days from a date.
Open the toolEveryday utilities
Word Counter
Count words, characters, lines and paragraphs as you type — with a reading-time estimate.
Open the toolQR Code Generator
Turn any text or URL into a scannable QR code and download it as a PNG, in your browser.
Open the toolImages to PDF
Merge JPG or PNG images into one PDF, right in your browser — nothing is uploaded.
Open the toolCharacter Counter
Count characters, words, lines, sentences and more as you type.
Open the toolLorem Ipsum Generator
Generate placeholder paragraphs, sentences and words for mockups.
Open the toolLine Sort and Dedupe
Sort, reverse, dedupe, trim and shuffle lists of lines.
Open the toolBarcode Generator
Render a scannable CODE128, EAN or UPC barcode and download an SVG.
Open the toolPassword Strength Checker
Rate a password and estimate offline brute-force time, locally.
Open the toolRandom Picker
Draw random winners from a list or shuffle it.
Open the toolText to Speech
Have the browser read any text aloud, with voice, rate and pitch.
Open the toolStopwatch
Start, stop and record lap times, built with the page clock.
Open the toolWord Frequency Counter
Rank words by how often they appear in your text.
Open the toolTyping Test
Measure words per minute and accuracy as you type.
Open the toolImage & PDF tools
Image Compressor
Shrink JPG, PNG or WebP files in your browser — nothing is uploaded.
Open the toolImage Resizer
Resize by pixels or percentage, keeping the aspect ratio, in your browser.
Open the toolImage Converter
Convert between JPG, PNG and WebP — no upload, no queue.
Open the toolMerge PDF
Combine two or more PDFs into one, locally with pdf-lib — nothing leaves your device.
Open the toolSplit PDF
Pull a page range out of a PDF into a new file, in your browser.
Open the toolPDF to JPG
Turn every PDF page into a downloadable JPG, rendered with pdf.js.
Open the toolImage Cropper
Drag a selection over an image and download just that region as a PNG.
Open the toolImage Rotate and Flip
Rotate or flip an image and download a PNG, on a local canvas.
Open the toolWord to PDF
Convert a .docx file to clean HTML, then print to PDF locally.
Open the toolRotate PDF
Rotate every page of a PDF by 90, 180 or 270 degrees.
Open the toolAdd Page Numbers to PDF
Add page numbers to every page in any corner or centred.
Open the toolImage Watermark
Tile watermark text across a photo and download a PNG.
Open the toolFavicon Generator
Resize any image to a square favicon PNG at 16 to 256 px.
Open the toolPDF Text Extractor
Pull all the text out of a PDF and download it as plain text, with pdf.js.
Open the toolPDF Compressor
Shrink a PDF in your browser by re-rendering each page and re-saving it locally. The file never leaves your device.
Open the toolText, color & math
Percentage Calculator
What is X% of Y, what % one number is of another, and increases or decreases.
Open the toolCase Converter
Switch text between UPPERCASE, Title Case, camelCase, snake_case and more.
Open the toolText Diff
Compare two versions of a text line by line and see what changed.
Open the toolMarkdown to HTML
Type Markdown and see the formatted HTML preview as you type.
Open the toolHex to RGB
Convert a hex color to RGB and HSL with a live preview swatch.
Open the toolColor Picker and Converter
Convert hex, RGB and HSL, sample from screen and check contrast.
Open the toolNumber to Words
Spell out integers from zero to trillions in English.
Open the toolSlug Generator
Turn a page title into a clean, URL-friendly slug.
Open the toolMeta Tag Generator
Build Open Graph and Twitter Card tags with a live preview.
Open the toolWCAG Color Contrast
Check WCAG AA/AAA contrast between two colors for accessible UI.
Open the toolUnit converters
Acres To Hectares
Convert acres to hectares instantly. Type a value and the result updates as you go
Open the toolCelsius To Fahrenheit
Convert Celsius to Fahrenheit instantly. Type a value and the result updates as you go
Open the toolCentimeters To Inches
Convert centimeters to inches instantly. Type a value and the result updates as you go
Open the toolCups To Millilitres
Convert US cups to millilitres instantly. Type a value and the result updates as you go
Open the toolFahrenheit To Celsius
Convert Fahrenheit to Celsius instantly. Type a value and the result updates as you go
Open the toolFeet To Meters
Convert feet to meters instantly. Type a value and the result updates as you go
Open the toolGallons To Liters
Convert US gallons to liters instantly. Type a value and the result updates as you go
Open the toolGrams To Ounces
Convert grams to ounces instantly. Type a value and the result updates as you go
Open the toolHectares To Acres
Convert hectares to acres instantly. Type a value and the result updates as you go
Open the toolInches To Centimeters
Convert inches to centimeters instantly. Type a value and the result updates as you go
Open the toolInches To Millimeters
Convert inches to millimeters instantly. Type a value and the result updates as you go
Open the toolKilograms To Pounds
Convert kilograms to pounds instantly. Type a value and the result updates as you go
Open the toolKilograms To Stone
Convert kilograms to stone instantly. Type a value and the result updates as you go
Open the toolKilometers To Miles
Convert kilometers to miles instantly. Type a value and the result updates as you go
Open the toolKilometres Per Hour To Miles Per Hour
Convert kilometres per hour to miles per hour instantly. Type a value and the result updates as you go
Open the toolLiters To Gallons
Convert liters to US gallons instantly. Type a value and the result updates as you go
Open the toolMeters To Feet
Convert meters to feet instantly. Type a value and the result updates as you go
Open the toolMeters To Yards
Convert meters to yards instantly. Type a value and the result updates as you go
Open the toolMiles Per Hour To Kilometres Per Hour
Convert miles per hour to kilometres per hour instantly. Type a value and the result updates as you go
Open the toolMiles To Kilometers
Convert miles to kilometers instantly. Type a value and the result updates as you go
Open the toolMillilitres To Cups
Convert millilitres to US cups instantly. Type a value and the result updates as you go
Open the toolMillimeters To Inches
Convert millimeters to inches instantly. Type a value and the result updates as you go
Open the toolOunces To Grams
Convert ounces to grams instantly. Type a value and the result updates as you go
Open the toolPounds To Kilograms
Convert pounds to kilograms instantly. Type a value and the result updates as you go
Open the toolSquare Feet To Square Metres
Convert square feet to square metres instantly. Type a value and the result updates as you go
Open the toolSquare Metres To Square Feet
Convert square metres to square feet instantly. Type a value and the result updates as you go
Open the toolStone To Kilograms
Convert stone to kilograms instantly. Type a value and the result updates as you go
Open the toolYards To Meters
Convert yards to meters instantly. Type a value and the result updates as you go
Open the toolWhy they run in the page
Most free tools online upload what you give them, process it on a server, then hand it back. That round trip is why some of them make you wait, why others cap your file size, and why a few want an account before showing you a result. These tools skip it entirely.
Three things follow from that. Nothing you paste is transmitted — a token you are debugging, a config file, a payload from a customer is read in the page and gone when you close the tab, which matters most for the tools people reach for at work. Results appear as you type, because there is no network call in the path. And nothing is metered: no size ceiling, no daily limit, no premium tier.
The trade-off is the mirror image. The work happens on your own hardware, so a very large file is limited by the memory your device has free. For the sizes these tools are built for — a few megabytes of JSON, a token, a spreadsheet of numbers — that ceiling is not one you will notice.
What you will not find here
This site used to carry product roundups and buying guides. Those have been removed, because a page recommending a specific appliance or gadget ages badly and is hard to keep honest. What is left is the part that does not expire: arithmetic, encoding, and formatting, done correctly and done locally.
The formulas behind every calculator are the standard ones and are shown alongside the result, so you can check the working rather than take a number on faith. Where a figure depends on your own situation — a loan rate, a currency rate, a body measurement — the tool asks you for it rather than assuming.