Crontab Generator

A cron expression is a string of 5 fields (minute, hour, day, month, weekday) that defines a recurring schedule. For example, '0 9 * * 1-5' means 'at 09:00, Monday through Friday'. Cron is used in Unix-like systems, GitHub Actions, AWS Lambda, and many CI/CD pipelines to schedule tasks.

An asterisk (*) means 'every valid value'. In the minute field, * means every minute. In the hour field, * means every hour. For example, '* * * * *' runs every minute, and '0 * * * *' runs at minute 0 of every hour (i.e., every hour on the hour).

Use the step syntax: '*/15 * * * *'. The */ syntax means 'every N', so */15 in the minute field means every 15 minutes starting from 0 (0, 15, 30, 45). Similarly, */5 means every 5 minutes and */2 means every 2 hours when in the hour field.

Day-of-month (field 3) specifies a calendar date (1–31). Day-of-week (field 5) specifies a weekday (0=Sunday through 6=Saturday). When both are set (not *), most cron implementations run the job when EITHER condition is true, not both — this is a common source of confusion.

Use commas to list multiple values. '0 8,12,18 * * *' runs at 08:00, 12:00, and 18:00 every day. You can also combine ranges and lists: '0 9 * * 1,3,5' runs at 09:00 on Monday, Wednesday, and Friday.