About Cron Humanizer

Explain a cron expression in English + show the next 5 run times. Part of the DevTools Surf developer suite. Browse more tools in the Date / Time collection.

Use Cases

• DevOps engineers verifying cron schedules before deploying to production
• Backend developers debugging why a scheduled job runs at unexpected times
• SREs translating inherited crontab entries into human-readable schedules
• Data engineers confirming ETL job timing across different timezones

Tips

• Paste your crontab line to see the next 5 scheduled run times
• Use the English translation to verify complex expressions like 0 */6 * * 1-5
• Check edge cases like February 30th or day-of-week vs day-of-month conflicts

Fun Facts

• The cron daemon was created by Ken Thompson for Unix Version 7 in 1979. The modern Vixie cron (by Paul Vixie, 1987) is still the default on most Linux distros.
• Cron expressions use 5 fields (minute, hour, day, month, weekday), but some systems like Quartz add a 6th field for seconds and a 7th for year.
• The '@reboot' cron shorthand runs a job once at system startup — it was added by Vixie cron and is not part of the original POSIX specification.

FAQ

What format does it expect?

Standard 5-field Unix cron (minute hour day month dayOfWeek), or 6-field with seconds (Quartz). Auto-detects which.

Does it show the next run?

Yes — next 5 executions in your local timezone. Helps verify the expression matches your intent.

Why does my cron not fire?

Common reasons: wrong timezone, daylight-saving transition, 'day of month' AND 'day of week' (either-or not both), or 31st of month in a 30-day month.

Accepts @daily, @weekly, etc.?

Yes — special strings (@hourly, @daily, @weekly, @monthly, @yearly, @reboot) are translated to their cron equivalents.