Cron expression checker
Check a five-field Unix cron schedule and preview its next matching minutes in a chosen time zone.
- 1Add input
- 2Adjust settings
- 3Get your result
Tool input and files are processed in this browser without being uploaded.
Before you start
Paste a five-field Unix cron time expression, choose the scheduler’s IANA time zone, and inspect the next five matching minutes. Day fields follow Cronie crontab syntax; the daylight-saving preview lists local-time matches, not guaranteed daemon executions.
How to use this tool
- Paste a five-field expression such as 0 9 * * MON-FRI. Enter the scheduler’s IANA time zone; UTC is the default.
- Optionally enter an ISO instant with Z or a numeric offset as the starting point. Leave it blank to start from now.
- Select “Check schedule”. Compare the next local and UTC times, especially around daylight-saving changes, before using the expression in your scheduler.
Supported inputs and limits
Five time fields only, without a command. Supports numbers, three-letter month and weekday names, lists, ranges and steps. Seconds, @aliases, L/W/#/?, random ~ and scheduler-specific extensions are not supported.
Shows up to five matches within 50 years after the chosen instant. Missing daylight-saving minutes are skipped; repeated local minutes appear with both UTC offsets. Daemon execution and time-zone rules may differ.
Input stays in this browser. This tool never runs a job or sends a command.
Worked example
Example input
0 9 * * MON-FRI
Example options
{"timezone":"UTC","reference":"2026-09-23T00:00:00Z"}Example output
The first five matching UTC times are 2026-09-23, 24, 25, 28 and 29 at 09:00.
When something does not work
Enter five time fields without a command. If the expression or time zone is rejected, check the named-field, range and ISO instant examples above. A schedule with no matching time in 50 years has no preview.
Frequently asked questions
Why do the day-of-month and weekday fields matter together?
Under the Cronie-style rule, when both fields are restricted, a match in either field can trigger the job. Check the listed dates before copying the expression to your scheduler.
Are daylight-saving changes included?
Yes. This browser preview lists matching local minutes in the selected IANA zone: nonexistent minutes are skipped and repeated minutes show both offsets. Cronie may immediately run a specific-time job missed during a forward clock change and avoid a duplicate run after a backward change; check your target daemon separately.
Is my input sent to a server?
No. Tool input is processed in your browser, not sent to a server. Temporary workspaces stay in the same tab and are cleared by a refresh or tab closure. Save the results you need.
Documentation & further reading
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