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TIME

Cron Expression Tester

Test a cron expression against a real clock: check whether it fires at an exact moment, see a month calendar of run days, count how many times it runs over the next 24 hours / week / month / year, and list the next and previous runs — in any timezone, with per-field validation.

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What this tool does

It checks a cron expression against a real calendar rather than just listing the next few runs. Use it to confirm a schedule does what you think before you deploy it.

Point-in-time check

Pick an exact date and time and the tool answers yes or no, and shows every field with a tick or a cross — so a near miss (0 9 * * 1 tested against a Tuesday) is obvious.

Month calendar

Every day the job runs at least once is highlighted. Click a day to see that day's exact run times.

Run count

Over the next 24 hours, 7 days, 30 days or 365 days, the tool reports how many times the job fires — a quick sanity check that * * * * * is 1,440 a day and */5 * * * * is 288.

Next and previous

The upcoming runs and the most recent past runs, both in your chosen timezone.

Privacy

Everything runs in your browser. Nothing is uploaded.

FAQ

Frequently asked questions

Why does my expression not fire on the date I expected?
Check the per-field ticks in the point-in-time panel. The usual cause is the weekday: cron weekdays are 0 (Sunday) to 6 (Saturday), and 1-5 is Monday to Friday, not Sunday to Thursday.
How is the run count calculated?
By scanning every minute (or second, for a six-field expression) in the window and counting matches. A one-year window on a per-minute job is 525,600 checks and is capped for performance — the tool tells you if it hit the cap.
Does it handle both day-of-month and day-of-week being set?
Yes. Standard cron runs the job when either the day-of-month or the day-of-week matches, so "0 0 1 * MON" fires on the 1st and on every Monday. The calendar and count reflect that OR behaviour.
Can I test in a timezone other than my own?
Yes. Pick any IANA timezone and the point-in-time check, calendar and next runs are all evaluated in that zone, daylight saving included.
What is the sixth field?
A leading seconds field: "*/30 * * * * *" runs every 30 seconds. Five fields is the classic minute-resolution Unix form.
Is anything sent to a server?
No. All parsing and scanning happen locally in your browser.
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