How to use it
- 1
Fill the individual fields or paste an existing cron expression.
- 2
Run syntax and range validation.
- 3
Review the explanation and the next UTC occurrence timestamps.
What the tool can do
- Wildcards, numeric values, lists, ranges, and steps.
- JAN–DEC month names and SUN–SAT weekday names.
- Vixie-style OR semantics when both day-of-month and day-of-week are restricted.
- Up to 10 future occurrences with a 366-day horizon and a hard timeout.
Common use cases
- Checking a schedule before adding it to crontab or a CI job.
- Finding an error in a range, list, or step.
- Checking when a schedule will run in UTC.
How it works inside
Expressions are limited to 256 characters, while preview is capped at 10 results, 366 days, and a fixed iteration limit.
Next-occurrence calculation runs in a dedicated same-origin Web Worker that is terminated on timeout, reset, or component unmount.
Questions and answers
Does it support a sixth seconds field?
No. The current contract is limited to the five-field Unix dialect: minute, hour, day-of-month, month, and day-of-week.
Why are results shown only in UTC?
UTC keeps preview deterministic and avoids claiming compatibility with a particular scheduler, timezone database, or DST rule set.