Free Online Developer Tools – Format, Validate & Convert

Format JSON into clean, indented code or minify it down to a single compact line. Broken input gets an error with the exact line and column, and recursive key sorting makes two files easy to compare.

Encode text to Base64 or decode a Base64 string back into readable text. A URL-safe option and full Unicode support are built in, and decoded images, PDFs or ZIPs can be saved as files.

URL encode text so it is safe inside a link, or decode percent-encoded strings back into plain words. Paste a full address to see every query parameter listed in a table with its decoded value.

Need a UUID generator for test data or database keys? Create random v4 or time-sortable v7 IDs, up to 1,000 at once, with or without hyphens, braces or capitals.

This hash generator calculates MD5, SHA-1, SHA-256, SHA-384 and SHA-512 together from text or any file. Paste a published checksum to see which algorithm matches, with nothing leaving your device.

Generate an MD5 hash of a word, a sentence or a whole file in a moment. A compare box checks it against an expected MD5 checksum while ignoring spaces and letter case.

Verify a download or fingerprint any text with a SHA-256 hash generator powered by the browser's Web Crypto engine. Large files show a progress bar and are hashed locally, never uploaded.

Decode a JWT to read its header and payload as tidy JSON, with exp, iat and nbf turned into real dates. Tokens stay on your device, and unsigned alg none tokens trigger a warning.

Convert a colour between HEX, RGB, HSL and OKLCH with one input, alpha included. The WCAG contrast ratio against white and black shows whether text in that shade will pass AA or AAA.

Convert JSON to CSV for Excel and other spreadsheets, or turn a CSV export back into JSON. Nested objects flatten into dot-named columns like address.zip, and the download keeps accented text readable.

Compare two versions of a text with a diff checker that marks every addition and deletion. Switch between line, word and character views, and ignore case or spacing changes when they do not matter.

Test a JavaScript regex against sample text and watch every match highlight as you type. Capture groups appear in a table, and a replace preview supports $1 and named group references.

Turn an image into Base64 or a data URI you can drop straight into HTML, CSS or Markdown. A size comparison shows how much larger the encoded version is, and SVGs can be URL-encoded instead.

Minify CSS with a structural optimiser that can merge duplicate rules, or beautify a minified stylesheet back into readable code. Bytes saved are shown, and licence comments are kept by default.

Compress JavaScript with Terser to shorten local names, fold constants and optionally strip console calls. Going the other way, Prettier reformats minified scripts, JSX included, so they are readable again.

Clean up messy markup with an HTML formatter that indents tags and tidies inline CSS and JavaScript too. A careful minifier removes whitespace and comments while leaving pre, textarea and script blocks untouched.

Convert Markdown to HTML with a side-by-side preview that updates while you type. Tables, task lists and GitHub-style heading ids are supported, and you can download a complete styled page.

Design a linear, radial or conic background with this CSS gradient generator and copy a single clean declaration. Add up to six colour stops, or hit the random button for balanced hues.

Stack up to six layers in a box shadow generator with sliders for offset, blur, spread and opacity. Inset and outer shadows can mix, and a matching Tailwind arbitrary class is generated too.

Build a cron expression with a visual picker or paste one to get a plain-English explanation. The next ten run times are listed in local time or UTC, and impossible dates like 30 February are flagged.