Cron Expression Parser

Validate a five-field cron expression and calculate its next scheduled run times.

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Try:

Result

Expression
*/15 9-17 * * 1-5
Next run (UTC)
2026-01-05T09:00:00.000Z
#UTC timeUnix time
12026-01-05T09:00:00.000Z1767603600
22026-01-05T09:15:00.000Z1767604500
32026-01-05T09:30:00.000Z1767605400
42026-01-05T09:45:00.000Z1767606300
52026-01-05T10:00:00.000Z1767607200
This parser uses UTC and standard five-field cron. Some platforms use local time, a seconds field or different day-of-week semantics.

About Cron Expression Parser

Inspect a standard minute-hour-day-month-weekday cron schedule and preview upcoming UTC runs before installing it in automation. Named shortcuts for common hourly, daily, weekly, monthly and yearly schedules are supported.

Cron field order

The five fields are minute, hour, day of month, month and day of week. Lists, ranges, wildcards and step values are expanded and validated before the schedule is searched.

Production scheduling

A syntactically valid expression is only part of a safe job. Confirm the host timezone, daylight-saving behaviour, job duration, overlap policy and retry handling. Redirect output to monitored logs and make the command idempotent where possible. For backups and maintenance, test restoration or rollback rather than assuming a successful exit means the objective was achieved. Platform extensions such as seconds, names or special characters are intentionally not inferred here.

Common use cases

  • Verify a backup schedule before deployment.
  • Convert an expression into concrete UTC times.
  • Troubleshoot ranges, lists and step syntax.

Edge cases and gotchas

  • A preview does not guarantee execution. Verify the service account, environment, working directory, path, locking, timeout and notification behaviour on the real scheduler, then monitor the first production runs and confirm the expected operational result.

Frequently asked questions

Which timezone is used?
All previews use UTC. Confirm the timezone configured by the actual cron service before deployment. If a job must follow local civil time, explicitly test daylight-saving transitions and document whether duplicate or skipped wall-clock times are acceptable.
Does this support Quartz cron?
No. Quartz commonly adds a seconds field and special operators. Use the scheduler’s own documentation and validator when deploying a non-standard cron dialect.