TontonTools

Cron Job Expression Builder

Build cron expressions — schedule jobs with a visual, error-proof builder.

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Updated Sep 2026
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How to use Cron Job Expression Builder

  1. Set each field — specific values, * for every, */n for steps, ranges like 1-5.
  2. Read the plain-English translation — confirm it means what you intend.
  3. Copy the expression into crontab, your host's cron panel, or CI schedule.
  4. Verify the server timezone — cron's clock is the machine's, not yours.

What is Cron Job Expression Builder?

A cron job expression builder constructs crontab schedule expressions from a visual interface — you set each field (minute, hour, day of month, month, day of week) and it produces the five-field expression plus a plain-English reading of when it runs. 0 3 * * 1 means "every Monday at 3:00 AM".

Cron syntax is compact and unforgiving: * is every, */5 is every fifth, 1-5 a range, 1,15 a list — and a small mistake doesn't error, it silently runs your job at the wrong time or 60× too often. Building visually with an English readback prevents exactly those silent failures.

About the Cron Job Expression Builder

Set each field and read the resulting cron expression alongside its plain-English meaning.

Common schedules everyone needs: nightly at 3am (0 3 * * *), every 15 minutes (*/15 * * * *), weekday mornings (0 8 * * 1-5), first of the month (0 0 1 * *), Sunday-night maintenance (0 23 * * 0). Where they go: server crontabs (crontab -e), hosting control panels' cron sections, CI schedules (GitHub Actions uses the same five fields), and framework schedulers.

The classic traps the builder makes visible: the day-of-month AND day-of-week fields are OR-combined when both are restricted (0 0 13 * 5 runs on the 13th AND every Friday, not just Friday the 13th), and cron runs in the SERVER's timezone (so "3am" is 3am wherever the machine thinks it is — verify before trusting a schedule, especially around DST). This is the same builder behind our Cron Expression Parser. Copy the expression into your crontab and confirm the timezone.

Frequently Asked Questions

Minute (0-59), hour (0-23), day of month (1-31), month (1-12), day of week (0-7, both 0 and 7 = Sunday), in that order. 30 2 * * 1 = Mondays at 02:30.
*/15 * * * * — the */15 means "every 15th minute". Don't confuse it with 15 * * * * (which runs once, at :15 past each hour) — a common mistake the plain-English readback catches.
Cron ORs them: 0 0 13 * 5 runs on every 13th AND every Friday, not only Friday the 13th. It's the spec's most surprising rule — achieving the AND needs a date check inside the job itself.
The server's — so "3am" is 3am wherever the machine is set, not your local time. Check the server timezone (and watch DST) before relying on a schedule, especially for time-sensitive jobs.
The expression (paste it here to confirm), the server timezone, whether the command works with cron's minimal PATH (use absolute paths), and the cron log for attempts. Most "cron didn't run" cases are one of those four.

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