Cron Expression Builder & Parser
Build cron schedules from presets or raw fields, then translate any expression into plain English. Validate your syntax before you deploy it.
Presets
Expression
Valid0 9 * * *
At 09:00.
Fields, left to right: minute, hour, day of month, month, day of week. Use * for “every”, */15 for a step, 9-17 for a range, and 1,15,30 for a list.
Note: when both day-of-month and day-of-week are restricted, most systems (Vixie cron) OR them together — one must match.
Frequently asked questions
What is a cron expression?
A cron expression has five fields — minute, hour, day of month, month, and day of week — describing when a scheduled job should run. For example, 0 9 * * 1 runs at 9:00 every Monday.
Can I use the @-shorthands?
Yes — the parser understands @reboot, @daily, @hourly, @weekly, @monthly, and @yearly, which are supported by cron implementations like cronie and Vixie.
Why is day-of-month + day-of-week tricky?
When both are restricted, classic cron ORs them, so a job runs if either matches. This is a common source of “why did it run on Tuesday?” surprises — keep one field as * if you are unsure.
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