Developer Tools
Handy utilities for developers: regex, cron, colors, and more
A growing collection of free, in-browser developer utilities. Test and debug regular expressions with live highlighting, translate and schedule cron expressions, check color contrast against WCAG accessibility thresholds, and look up HTTP status codes and MIME types — all running entirely on your device, with nothing uploaded.
Regex Tester
Test and debug regular expressions with live match highlighting, capture groups, and replace.
Color Contrast Checker
Check color pairs against WCAG contrast requirements with a live preview and color-format conversion.
MIME Type Lookup
Find the MIME type for a file extension, or the extensions for a MIME type
URL Parser
Break a URL into its components and list its query parameters
JSON Schema Generator
Generate a JSON Schema from a sample JSON payload, inferring types, formats, and required properties
HTTP Status Code Lookup
Search and look up every HTTP response status code by number or name
Cron Expression Parser
Translate cron expressions to plain English, preview run times, and build schedules
Semver Calculator
Parse, bump, compare, and range-test semantic versions