Free Developer Tools
25 Free Tools
Quick helpers for everyday coding. Format, validate or minify JSON, encode and decode Base64 and URLs, read a JWT, test a regular expression, tidy or minify HTML, CSS, JavaScript and SQL, make UUIDs and convert between YAML, JSON and CSV. Everything runs in your browser, so the API responses, tokens and config you paste aren't sent anywhere.
JSON FormatterFormat JSON so it is easy to read, with your choice of indent and sorted keys. Errors show the exact line and column.JSON ValidatorCheck if your JSON is valid as you type. See the exact line and column of any error, and fix common mistakes in one click.JSON MinifierRemove all spaces and line breaks from JSON to make it as small as possible for APIs and config files.Base64 Encoder / DecoderEncode text to Base64 or decode Base64 back to text. Handles emoji and accents (UTF-8) and URL-safe Base64 from JWTs.URL Encoder / DecoderEncode text for use in a web address (spaces become %20), decode it back, or split a URL into its parts.HTML FormatterTidy messy or minified HTML into neatly indented code that is easy to read and edit.CSS FormatterTurn minified or messy CSS into clean, indented code with one property per line.JavaScript FormatterMake minified or messy JavaScript readable again, with proper indentation and line breaks.CSS MinifierShrink CSS for faster websites: remove spaces and comments, shorten colours and values, and merge duplicate rules.JavaScript MinifierMinify JavaScript with Terser: shorter names, no comments or spaces, and dead code removed. Works with modern JS.UUID GeneratorGenerate random UUIDs (GUIDs) — v4 or time-ordered v7 — up to 1,000 at once, and check what any UUID contains.Timestamp ConverterConvert Unix timestamps to dates and back, in your own time zone or other common ones. Seconds, milliseconds, microseconds and nanoseconds.JWT DecoderDecode a JSON Web Token (JWT) to read its header, claims and expiry date. Nothing is sent anywhere.Regex TesterTest JavaScript regular expressions live: see every match highlighted, the capture groups, and a replace preview.Color ConverterConvert colours between HEX, RGB, HSL, HSV, CMYK and OKLCH, check text contrast, and get lighter and darker shades.SQL FormatterFormat long SQL queries into clean, readable code. Supports MySQL, PostgreSQL, SQL Server, Oracle, SQLite and more.XML FormatterFormat and validate XML: indent it neatly, or minify it. Errors show exactly what is wrong.YAML to JSON ConverterConvert YAML to JSON and JSON to YAML — handy for Kubernetes, Docker Compose, GitHub Actions and config files.YAML Formatter & ValidatorCheck YAML for errors (with the line and column) and tidy it: consistent indents, optional sorted keys — for Kubernetes, Docker Compose and CI files.CSV to JSON ConverterConvert CSV (from Excel or Google Sheets) to JSON, or JSON back to CSV. Quotes, commas and line breaks inside cells are handled.JSON to CSV ConverterTurn JSON into a CSV file for Excel or Google Sheets. Nested objects become columns like address.city, and you can download the result.Markdown to HTMLWrite or paste Markdown and see it turn into HTML as you type. Copy the HTML or download it as a web page.Text Diff CheckerCompare two texts and see exactly what changed — added parts in green, removed parts in red. By line, word or character.HTML Entity EncoderEncode text for HTML (& < > " become & < …) or decode HTML entities back into normal text.Number Base ConverterConvert numbers between binary, octal, decimal, hexadecimal and any base up to 36. Very large numbers work too.
Guides
- JSON Explained: How to Format, Validate and Fix Common Errors
- Base64, URL Encoding and JWTs: What They Are (and Why They're Not Encryption)
- Regular Expressions for Beginners: A Practical Guide With Examples
- Unix Timestamps Explained: Seconds, Milliseconds and Time Zones
- Cron Expressions Explained: Read and Write Schedules Without Mistakes
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