Free Developer Tools, in Your Browser

Format JSON, XML, HTML, CSS, JavaScript and SQL. Test regex, encode Base64 and URLs, decode JWTs, generate UUIDs and hashes, convert timestamps and colours, preview Markdown and HTML, build cron expressions and QR codes — free, with no signup and no watermark. Your code never leaves your browser.

All developer tools

JSON Formatter and ValidatorFormat, validate and minify JSON in your browser. Invalid JSON shows the exact error so you can fix it fast.JSON to XML ConverterConvert JSON objects and arrays to readable XML, entirely in your browser.XML Formatter and ValidatorPretty-print XML and validate its structure using the browser DOM parser. No uploads.HTML Formatter and MinifierFormat HTML for readability or minify it for smaller files, using Prettier in your browser when available.CSS Formatter and MinifierFormat CSS with consistent indentation or minify it to reduce file size.JavaScript Formatter and MinifierFormat JavaScript for readability or minify it, with Prettier in the browser when available.SQL FormatterFormat SQL queries with proper indentation and uppercase keywords using sql-formatter.Code Diff CheckerCompare two texts or code snippets line by line, with added lines in green and removed lines in red.Regex TesterTest JavaScript regular expressions live, see all matches highlighted, and check capture groups.Base64 Encoder and DecoderEncode text to Base64 or decode Base64 back to text, with proper UTF-8 handling.URL Encoder and DecoderEncode text for safe use in URLs, or decode percent-encoded URLs back to readable text.JWT DecoderDecode a JWT header and payload in your browser. This tool does NOT verify the signature.UUID GeneratorGenerate secure random UUID v4 values with crypto.randomUUID, one at a time or in bulk.Hash GeneratorGenerate SHA-256, SHA-384, SHA-512 and SHA-1 hashes with the Web Crypto API.Unix Timestamp ConverterConvert Unix timestamps to dates and dates to timestamps, in seconds or milliseconds.Color Picker and HEX/RGB ConverterPick a colour and convert between HEX, RGB and HSL, with a live preview swatch.Markdown PreviewerWrite Markdown and see the rendered HTML preview live, in your browser.HTML PreviewerPreview HTML instantly in a sandboxed iframe. Your code runs isolated from this page.Lorem Ipsum GeneratorGenerate placeholder paragraphs, sentences or words for designs and layouts.Cron Expression GeneratorBuild a cron expression from fields and read a plain-English description of when it runs.QR Code Generator for DevelopersGenerate a QR code for a URL or text, with size and colour options and a PNG download.

Why use UMARIX Developer Tools?

Private by design: tools run locally in your browser. No code is uploaded by default.
No account, no watermark, no artificial usage limits.
Honest tools: JWT decoding is clearly labelled as not verifying signatures, and MD5 is not falsely claimed via Web Crypto.

New here? Read the developer guides or the frequently asked questions.