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Cron Time Zone and DST Simulator
Time and date
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About this tool
Parse numeric five-field Cron with an IANA zone, explicit start and execution count; inspect skipped and repeated local times.
Common uses
- Check scheduled jobs deployed in a different time zone.
- Inspect skipped or repeated executions around daylight-saving transitions.
- List future executions from an explicit instant with UTC equivalents.
How to use it
- 1.Enter numeric five-field Cron, an IANA zone and an ISO start containing Z or an offset.
- 2.Choose 1–50 executions and whether repeated local times run twice, earlier only or later only.
- 3.Simulate and inspect local times with offsets, UTC instants and transition diagnostics.
Limits and notes
- Numeric five-field Cron only: minute, hour, day, month and weekday; supports *, lists, ranges and steps, without names, seconds, L/W/#/?, or @ aliases.
- Uses Cronie DOM/DOW star semantics: AND if either day field starts with *, otherwise OR. Sunday accepts 0 or 7.
- Matches minutes strictly after the start instant. Nonexistent times are skipped; repeated times follow your selected policy. Daemon catch-up is not simulated.
- Up to 50 executions over five years; expressions are limited to 256 characters and calculation has a timeout.
- Diagnostics cover inspected dates only, up to 200 entries; the final inspected day can include events after the last displayed execution. Zone data depends on the browser runtime.
Frequently asked questions
Do repeated times always run twice?
Choose both occurrences, the earlier occurrence, or the later one. Each execution shows its UTC offset and instant.
Does this exactly reproduce my server Cron?
It uses explicit five-field syntax and transition policies. Confirm catch-up, downtime and restart behavior with your actual scheduler.