Regex & Cron
Test regular expressions and parse cron expressions.
About Regex & Cron
The Regex and Cron Tester combines two essential developer tools in one interface: a real-time regex matcher with syntax highlighting and a cron expression parser with schedule visualization. Test patterns and schedules side by side without switching between tools.
The regex panel supports JavaScript, Python, and PCRE flavors with live matching as you type. The input text is highlighted to show matches, captures, and named groups in distinct colors. A detailed match info panel lists each match index, the full match text, and every capture group so you can debug complex expressions without guesswork.
Common regex patterns are available from a built-in snippet library: email validation, URL parsing, date formats, phone numbers, and more. Each snippet includes a brief explanation of what it matches and any known edge cases. You can also save your own patterns to a personal library tied to your browser storage.
The cron panel accepts standard 5-field (minute, hour, day, month, weekday) and 6-field (plus year) expressions. It displays the next 10 execution times in your local timezone, a human-readable description of the schedule, and a visual timeline showing which hours and days are active. Invalid cron expressions show a parsing error with suggestions for correction.
Special cron extensions are supported: L, W, and # for day-of-month and day-of-week, @yearly/@monthly shorthands, and common non-standard macros like @hourly and @reboot. The parser also handles timezone-aware expressions and can display UTC and local times simultaneously.
The combined layout is especially useful for developers debugging scheduled tasks that involve regex-based log parsing. You can test your cron schedule on one side and validate the regex pattern that processes the output on the other, all within a single viewport.
Frequently Asked Questions
What regex flavors are supported?
JavaScript (ECMAScript), Python, and PCRE (PHP). Flavor selection changes the matching behavior — for example, lookbehind assertions differ between JavaScript and PCRE. The tool notes flavor-specific differences inline.
Does the cron tool handle timezones?
Yes. You can set an explicit timezone for the cron expression. The next-execution table displays times in both the configured timezone and UTC.
Can I test a regex against a large file?
The inline editor handles inputs up to 100KB. For larger files, use the file upload option which streams the content and displays matches in a paginated results view.
What cron shorthand macros are supported?
@yearly, @monthly, @weekly, @daily, @hourly, and @reboot. These expand to their standard 5-field equivalents and show the same visualization as regular expressions.
Is there a way to share my regex or cron expression?
Yes. Each panel has a share button that generates a URL encoding the current pattern or expression along with the test input. Recipients see the exact same state without needing an account.