CodeClean
Code formatting, diffing, regex testing, and minifying
Free Developer Tools
Small utilities you reach for in the middle of a task: format and validate JSON, decode Base64 or a JWT, test a regular expression, build a cron schedule, format SQL, diff two files, check DNS or an SSL certificate.
Most of them run locally in the tab, which matters when the payload is a production config or a customer record.
Start with these
- QuickRef.dev In-browser code execution covers Python, JavaScript, SQL, and more with cheat sheets and snippet help.
- CodeClean It formats, beautifies, diffs, and minifies JSON, JavaScript, CSS, HTML, and SQL in the browser.
- DataKit It handles JSON/CSV conversion, viewing, editing, duplicate removal, merge/split, and validation client-side.
Want to know whether a tool uploads your files? See how browser-based tools work.
25 tools shown
Format and compare code
Use these when you need to clean up, diff, or minify code and text.
Convert and validate data
Reach for these to transform JSON, CSV, XML, and related data locally.
Encode and generate
Use these for passwords, IDs, Base64, URL, and other browser-side generators.
Build diagrams and charts
Choose these to create charts, diagrams, or schema visuals from your data.
Test sites and networking
Use these to inspect page speed, Core Web Vitals, or network and SSL issues.
Preview content and metadata
Pick these when you need markdown, screenshots, favicons, or social preview tags.
Questions about Free Developer Tools
Is it safe to paste API responses into an online formatter?
Prefer tools that run client-side, and strip tokens and personal data first. If in doubt, check the Network tab for requests while you paste.
Why use a web tool instead of an IDE plugin?
Speed and zero setup: they work on any machine, including a locked-down work laptop or a phone.