Cron Expression Explainer, Builder & Tester
Paste any cron expression for a plain-English meaning, the next runs in your timezone, and warnings before it bites you in production.
Help shape Cron Expression Explainer, Builder & Tester
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Frequently Asked Questions
No. Parsing, scheduling, timezone maths and the crontab analyzer all run in your browser, and your saved schedules stay in this browser's local storage. Nothing is uploaded — it works offline too.
In standard cron, when both day-of-month and day-of-week are set, a day matches if EITHER matches — so it runs on the 1st and on every Monday. The review flags this and shows how to get “first Monday” instead.
Unix has 5 fields and weekdays 0–7 from Sunday. Quartz adds seconds and an optional year, numbers weekdays 1–7 from Sunday and requires “?” in one day field. AWS uses minute-first with a year field. The Code tab converts between them.
On spring-forward days a time like 02:30 doesn't exist, and on fall-back days 01:30 happens twice. The Daylight saving tab lists every change in the next two years and exactly which of your runs are affected.
Yes. Switch to “Analyze a crontab / YAML” and paste it or drop the file. Every job is explained and validated, and you get a weekly load heat-map plus staggered suggestions for jobs that start at the same minute.