Free developer tools that run entirely in your browser

No sign-up, no file uploads, no data leaves your device. Format JSON, test regex, build cron expressions, generate passwords, and more — instantly.

Drag a tile by its handle to reorder them — your layout is saved in this browser only.

Beautify, minify, validate, and diff JSON with clear error locations.

Test patterns with live match highlighting and a plain-English explainer.

Build and decode standard, Quartz, and Kubernetes cron schedules.

Generate strong passwords and UUID v4 or time-sortable v7 identifiers.

Encode and decode text or files, plus decode JWTs, to and from Base64.

Convert HEX, RGB, and HSL, sample from an image, and check WCAG contrast.