Cron Expression Explainer
Runs entirely in your browser — nothing you type is sent anywhere.
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The mistake this tool is built to catch
When a cron expression restricts both the day of the month and the day of the week, cron runs when either matches — not both. So 0 0 13 * 5 is not “midnight on Friday the 13th”; it is “midnight on every 13th and every Friday”. Most explainers say “and” and quietly mislead you. This one detects the case and says so.
Explanations derived, not guessed
Every field is expanded to the exact set of values it matches, and the sentence is generated from those sets — so the prose cannot disagree with the schedule. Vendor extensions like L, W and # are refused by name rather than mis-explained, because a confident wrong answer about a production schedule is worse than no answer. And as with every tool here, the page is static and keeps working offline, verified by our automated tests on every release.