About this site

Cron Expression Generator & Explainer is a small, free developer tool built and maintained by an independent developer who got tired of re-deriving */5 * * * * from memory and second-guessing weekday numbers at 2 a.m. It does one thing: turn cron expressions into plain English (and back), with a live preview of the next run times.

Accuracy principles

• One dialect, done properly. The parser implements standard 5-field cron following Vixie cron semantics — including the day-of-month/day-of-week OR rule and 0-or-7-for-Sunday — rather than a vague mixture of dialects. AWS EventBridge and Quartz differences are documented on separate pages instead of being silently blended in.
• Tested logic. The parse/explain/next-run engine ships with a test suite of known expressions and expected outputs that must pass before any update goes live.
• Honest about timezones. Next-run previews are computed in your browser's local timezone and follow your OS clock for daylight saving. We say so next to the results, because a preview that pretends to know your server's timezone would be a lie.
• No fabricated claims. Where behaviour differs between cron implementations (DST handling, macros, steps), the pages say "most" or name the implementation instead of asserting a universal rule.

Privacy by architecture

The whole tool is static files plus client-side JavaScript. Expressions you type are parsed in your browser and never transmitted to us — there is no backend to send them to. See the privacy policy for the full picture, including the advertising disclosure.

Found a bug?

If an explanation reads wrong or a next-run time looks off, please send the exact expression — reproducible reports are the fastest way to make the tool better for everyone.