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Cron explainer

Paste a cron expression and read what it actually does, then check that against when it would next fire.

Both together on purpose: a sentence can be misread and five times could be a coincidence, and the two agreeing is what makes them convincing.

*/15 minute* hour* day of month* month* day of week

Every 15 minutes, every day.

The next five runs

In UTC.

Try one of these

Questions

Is what I paste sent anywhere?
No. Every tool in this kit runs in the page itself. There is no server here that receives what you paste, and you can check it in your browser's network tab: using a tool produces no request carrying your input at all.
Which syntax does it understand?
The standard five fields: minute, hour, day of month, month, day of week. Ranges like 1-5, steps like */15 and 0-30/10, lists like 1,15,30, and names like MON or JAN, in any case. Sunday can be written 0 or 7.
Why does setting both the day of month and the day of week run more often than I expect?
Because cron treats them as either, not both. An expression like 0 0 13 * FRI runs on the 13th of every month AND on every Friday. It looks like a bug, every cron implementation shares it, and the explanation says so out loud whenever both fields are set.
Are @daily and the other shorthands supported?
No, and deliberately. Half-supporting a syntax is how somebody comes to trust an answer that is wrong. The tool says what @daily is in five fields rather than guessing.
Why does it say a schedule never runs?
Because some cannot. The 30th of February is a valid expression that no clock will ever match. Rather than search forever, the tool looks eight years ahead and tells you it found nothing.

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