Cron Expression Tester

Paste a 5-field crontab expression and get a readable description plus the next 10 run times, in your timezone and UTC side by side. Because the job firing at 03:00 on your laptop and 20:00 on the server is how most cron stories begin.

Syntax this tester supports

• * every value, */15 every 15th value
• 1-5 ranges, 1-10/2 stepped ranges, 1,15,30 lists, and combinations like 0-20/5,45
• Month and weekday names: JAN-DEC, SUN-SAT (case-insensitive)
• 0 and 7 both mean Sunday in the day-of-week field
• Standard OR semantics when both day-of-month and day-of-week are restricted, matching Vixie cron

Non-standard extensions like @daily, L, W, #, and 6-field seconds syntax aren't supported; those vary between implementations and this tester sticks to what plain crontab guarantees everywhere.

The classic cron failure isn't the schedule

Most cron incidents have nothing to do with the expression. The job stops running because a server was rebuilt, a deploy wiped the crontab, disk filled up, or the script started exiting 1 and nobody saw the mail. Cron itself never tells anyone; it just quietly stops. The reliable fix is a dead man's switch: the job pings a URL on every successful run, and something alerts you when the ping doesn't arrive on schedule.