Cron Parser

How to use it

1. Paste a five-field cron expression, for example */15 9-17 * * 1-5.
2. Each of the five cells below explains one field in plain language.
3. The list at the bottom shows the next five runs in your browser local timezone.
4. When both day-of-month and day-of-week are restricted, a note explains the Vixie OR rule that applies.
5. A sample expression loads on open; edit or press Parse to recompute.

Common use cases

• Reading crontabs: decoding a schedule someone else wrote before touching it.
• Writing schedules: checking that 0 9 * * 1-5 really means weekday 9 AM.
• Debugging: seeing the next five runs to understand why a job fires (or does not) today.
• On-call handovers: a quick human-readable view of maintenance windows.

Why it stays private

The expression is parsed and simulated in your browser: no requests, no logging. The next-run list is computed by stepping through local-time minutes, so it reflects your machine timezone, which may differ from the server timezone where the cron actually runs.

FAQ

Q: What cron syntax is supported? A: The classic five fields (minute 0-59, hour 0-23, day of month 1-31, month 1-12, day of week 0-7 with 7 = Sunday) using numbers, *, comma lists, hyphen ranges and / steps. Names like MON or JAN and the shorthand strings @daily are not supported.

Q: What happens when day-of-month and day-of-week are both restricted? A: Vixie cron treats them with OR semantics: a day runs when either the day-of-month or the day-of-week matches. The tool follows that rule and shows a note whenever both fields are restricted.

Q: Why can the next runs differ from my server? A: The preview uses your browser local timezone, while crontab usually uses the server timezone. If they differ, the wall-clock times will match but the UTC instants will not.