Cron Expression Parser
Build and understand cron expressions — five fields, translated to English.
How to use Cron Expression Parser
- Set each field — specific values, * for every, */n for steps, ranges like 1-5.
- Read the plain-English translation — confirm it says what you meant.
- Copy the expression into crontab, your host's cron panel or CI schedule.
- Mind the server timezone — cron's clock is the machine's, not yours.
What is Cron Expression Parser?
A cron expression builder turns crontab's five cryptic fields — minute, hour, day-of-month, month, day-of-week — into something you can read and construct: 0 3 * * 1 becomes "every Monday at 03:00", and "every 15 minutes on weekdays" becomes */15 * * * 1-5.
Cron syntax is dense and unforgiving: * means every, */5 every fifth, 1-5 a range, 1,15 a list — and a mistake doesn't error, it silently runs your job at the wrong time (or 60× too often, the classic * * * * *-instead-of-hourly incident). Building visually with a plain-English readback prevents exactly that.
About the Cron Expression Parser
Set each field — minute, hour, day, month, weekday — with values, ranges or steps, and read the resulting expression alongside its plain-English meaning.
The expressions everyone eventually needs: nightly at 3am (0 3 * * * — off-peak convention), every 15 minutes (*/15 * * * *), weekday mornings (0 8 * * 1-5), first of the month (0 0 1 * *), and Sunday-night maintenance (0 23 * * 0). Where they go: server crontabs (crontab -e), hosting control panels' cron sections, CI schedules (GitHub Actions' schedule: uses the same five fields), and framework schedulers that accept raw cron.
The two classic traps the builder makes visible: day-of-month and day-of-week are OR-combined when both are restricted (0 0 13 * 5 fires on the 13th AND on every Friday — not just Friday the 13th); and cron runs in the server's timezone, so "3am" is 3am wherever the machine thinks it lives — verify before trusting a schedule across DST.