Cron Expression Builder & Next-Run Calculator
Validate five-field cron expressions and preview the next run times in local and UTC time. Everything runs in your browser — no schedules are sent anywhere.
A five-field expression is validated and the next run times are previewed in both local time and UTC. Because cron follows the server's timezone, a 3:00 AM job shifts by an hour across daylight saving time.
Tool workspace
Five Fields
Minute, hour, day of month, month, and day of week (0-6, Sunday to Saturday). Each field supports *, steps like */15, ranges like 9-17, and lists like 1,15.
Next Run Times
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How to Validate a Cron Expression Online
Learn how to validate five-field cron expressions and preview the next run times locally in your browser.
- 1
Enter or pick an expression
Type a five-field cron expression or choose a preset like every 15 minutes.
- 2
Review the field breakdown
Check minute, hour, day of month, month, and day of week values for obvious mistakes.
- 3
Read the next run times
See the next five executions in local time and UTC.
- 4
Copy the verified expression
Copy the expression into your scheduler and keep the same timing rules.
Common Use Cases
- 1Validate cron expressions before deploying them to CI schedulers or servers
- 2Preview when backups, reports, or cleanup jobs will actually run
- 3Convert time-based requirements into a schedule you can paste into crontab
- 4Debug legacy cron jobs whose timing no one remembers
Frequently Asked Questions
What do the five cron fields mean?
The standard five-field format is: minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-6, where 0 is Sunday). A wildcard * means 'every value' in that position.
Are my schedules uploaded anywhere?
No. The expression is parsed and the next run times are computed entirely in your browser. Nothing is sent to a server or stored.
How do I compute the next run time for a schedule?
The tool walks forward minute by minute and shows the next five matches in both your local time zone and UTC, which is the format most schedulers expect.
How does the tool handle daylight saving?
Next-run times are calculated in the IANA time zone you select, including the spring-forward gap where a local time does not exist. Each result is also shown in UTC, which is what most schedulers store.
Why is a six-field expression rejected?
The parser evaluates the standard five-field cron syntax. A sixth field usually belongs to a seconds-based variant, so remove it or convert the schedule before testing.
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You are responsible for key management and output validation.