Build and validate cron expressions with a visual editor showing next 10 execution times.
Turn a proposed crontab schedule into an expression you can inspect before using it. The editor exposes the schedule's minute, hour, day-of-month, month, and day-of-week fields, validates the resulting expression, and shows its next 10 execution times. The most important surprise is that a syntactically valid expression is not necessarily portable between cron implementations. Field counts, supported extensions, and the interaction between day-of-month and day-of-week can differ, so compare the preview with the scheduler that will actually run the job.
A crontab expression represents selections across five time fields in order: minute, hour, day of month, month, and day of week. The editor lets those selections be assembled visually and validates the combined text. Wildcards and other accepted operators affect a field's set of matching values; an invalid combination should be corrected before the occurrence list is trusted.
After an expression is accepted, the editor evaluates the schedule against calendar dates and presents the next 10 matches in chronological order. This list is the practical interpretation of the expression: it reveals repeated weekdays, month boundaries, and gaps that are hard to spot in compact cron notation. It does not install the expression or execute a command.
No. Validation says the editor can interpret the expression and calculate occurrences. A real run also depends on the target cron implementation, the crontab being installed, daemon state, permissions, command path, environment, and host time zone. Use the preview to check timing, then test the complete crontab in its target environment.
Traditional crontab semantics can treat those two restricted fields as alternatives: a date may match when either field matches, rather than only when both match. This behavior is dialect-sensitive. Inspect the 10 listed dates and consult the documentation for the scheduler that will consume the expression before relying on a combined restriction.
The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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