About Unix Cron Visualizer

Visualize cron schedules as a timeline of next executions. Part of the DevTools Surf developer suite. Browse more tools in the Generators collection.

Use Cases

• Verify scheduled job timing before deploying to production
• Debug why a cron job is not running at expected times
• Plan maintenance window schedules with visual confirmation
• Document recurring task schedules for operations runbooks

Tips

• See the next 10 execution times for any cron expression
• Validate complex expressions with day-of-week fields
• Hover over each field to see which values are active

Fun Facts

• Cron was written by Ken Thompson for Unix Version 7 in 1979; the modern Vixie cron, written by Paul Vixie, became standard in 1987.
• The cron expression '* * * * *' fires every minute, executing a job 525,600 times per year.
• The @reboot special string in cron, which runs a job once at startup, was a Vixie cron extension and is not part of the POSIX standard.

FAQ

What does the timeline show?

Next N executions of a cron expression on a visual timeline. Useful for spotting gaps, unexpected clusters, or sanity-checking seasonal jobs.

How far ahead does it project?

Up to 365 days by default. Toggle higher for yearly or leap-year concerns; lower for quick 'will it run tonight?' checks.

Does it handle DST transitions?

Yes — in timezones with DST, cron jobs near the transition hour either skip or double-fire. The visualizer marks these edge cases clearly.

Can I compare multiple expressions?

Yes — paste several and they overlay on the same timeline. Useful for planning when batch jobs collide.