Developer tools for common tasks
Small utilities for everyday development work. They run in your browser, so pasted payloads and tokens are not sent anywhere. Decoding a JWT shows its contents; only signature verification with the right key says anything about authenticity.
Validate and format development data
JSON formatter and validator
Format, minify and validate JSON with exact error positions and a tree view.
YAML and XML formatter and validator
Validate and format YAML or XML, and convert either to JSON.
Code formatter and minifier
Format or minify HTML, CSS and JavaScript (and TypeScript, JSON, Markdown).
Encoding toolkit
Base64, Base64URL, URL encoding, HTML entities, hex and Unicode escapes.
Test patterns and run queries
Inspect identifiers, tokens and schedules
UUID generator
Generate UUID v4, v7, v1 or name-based v5 identifiers in bulk, and validate UUIDs.
JWT decoder
Decode a JWT's header and payload, read its dates, and verify the signature with a key.
Cron expression builder and explainer
Build cron schedules, explain them in plain English and preview the next runs.
Unix timestamp converter
Convert Unix timestamps (seconds, ms, µs) to dates and back, in any time zone.
Guides
- Cron expressions explained, with examples: How the five cron fields work, common schedules, the day-of-month and day-of-week trap, time zones, and why some cron jobs never run.
- Unix timestamps and time zones explained: What a Unix timestamp is, how to tell seconds from milliseconds, how offsets differ from time zones, and the daylight-saving bugs that catch everyone once.