Free Online Developer Tools Eight small developer tools that work as you type and don't send your input anywhere. Most used: the JWT decoder , Base64 encoder , hash generator and UUID generator . To format JSON or compare two files, use the JSON formatter , the diff checker or the CSS formatter .
How to use Developer Utilities Choose a tool from the groups below, or press Ctrl+K anywhere and type its name. Paste your token, text or value. The JWT decoder and the encoder have a Sample button to try them first. Read the result, which updates as you type, and use Copy to take it with you. Frequently asked questions Is it safe to paste tokens and secrets here? The encoder, hash, JWT, UUID, password, timestamp and cron tools run entirely in your browser and don't send your input to a server. What's My IP is the one utility that contacts the server, because it needs to see your connection. As with any website, prefer test values over live production secrets.
Do these tools work offline? Once the page has loaded, everything except What's My IP works without a connection, since it is all computed locally.
Are the developer tools free? Yes. There is no account, no rate limit and no sign-up.
Is there a JSON formatter or diff tool? Yes, as their own pages: the JSON formatter and viewer validates, formats and explores JSON, the diff checker compares two texts or files, and the CSS formatter beautifies or minifies stylesheets.
What each tool does Encode and decode: read and verify a JWT (HS, RS, PS, ES and EdDSA); convert Base64, URL encoding, HTML entities and hex both ways; hash text or files with MD5, SHA-1, SHA-256, SHA-384, SHA-512 or HMAC. Generate: UUID v4 and v7, ULID and NanoID in bulk; passwords, passphrases and PINs with an entropy meter. Date and time: convert Unix timestamps to dates and back; read a cron expression in plain English with its next run times. Network: see your public IP address and what your browser reveals. Format and compare: JSON formatter , diff checker and CSS formatter . Related tools JWT Decoder & Encoder : Decode, verify and sign JSON Web Tokens with HS, RS, PS, ES or EdDSA, and check their expiry.Encode / Decode : Base64, Base64URL, URL, HTML entities, Unicode escapes and hex, both ways, as you type.Hash Generator : MD5, SHA-1, SHA-256, SHA-384 and SHA-512 of text or files, with optional HMAC key.JSON Viewer : Paste JSON to validate, format, minify and explore it as a collapsible tree.Diff Checker : Compare two texts or files side by side. Line and word highlights, JSON mode, ignore whitespace, export a patch.CSS Formatter : Beautify messy CSS or minify it for production. Handles nesting, @media and comments.All tools Board : Hand-drawn whiteboard with live to-do, code, table and API cards. Multiplayer and encrypted.Diff Checker : Compare two texts or files side by side. Line and word highlights, JSON mode, ignore whitespace, export a patch.JSON Viewer : Paste JSON to validate, format, minify and explore it as a collapsible tree.CSS Formatter : Beautify messy CSS or minify it for production. Handles nesting, @media and comments.Developer Utilities : JWT decoder, Base64/URL/HTML encoder, hashes, UUID/ULID and password generators, timestamp converter, cron explainer and what's my IP.JWT Decoder & Encoder : Decode, verify and sign JSON Web Tokens with HS, RS, PS, ES or EdDSA, and check their expiry.Encode / Decode : Base64, Base64URL, URL, HTML entities, Unicode escapes and hex, both ways, as you type.Hash Generator : MD5, SHA-1, SHA-256, SHA-384 and SHA-512 of text or files, with optional HMAC key.UUID / ID Generator : Bulk UUID v4 and v7, ULID and NanoID. Paste an ID to read its version and timestamp.Password Generator : Strong random passwords, EFF-wordlist passphrases and PINs, with an entropy and crack-time meter.Timestamp Converter : Unix seconds or milliseconds ↔ ISO, local, relative and world-clock times.Cron Expression Explainer : Read a crontab schedule in plain English, see its next run times and check each field as you type.What's My IP : Your public IP address, IPv4 or IPv6, approximate location, and what your browser reveals.PDF Tools : Edit and sign, merge, split, compress, convert (Word, Excel, PowerPoint, JPG), OCR, protect, unlock, redact and compare PDFs. Files stay on your device.Image Tools : Compress, resize, crop and convert (HEIC to JPG, WebP, AVIF, Base64). Optimise and render SVGs. Generate QR codes, favicons and OG images.Text Tools : Count words and characters (Hindi too) against a character limit, and convert text to UPPER, Title, camelCase, snake_case and more.Calculators : Age on any date, percentages, GST and marks, and a unit converter with sq ft, gaj, acre, guntha and KB vs KiB.What's new About Privacy