Cron expression decoder
& monitoring calculator

Five asterisks means "every minute". The fields, left to right, are: minute (0–59), hour (0–23), day of month (1–31), month (1–12), and day of week (0–7, where both 0 and 7 are Sunday). An asterisk means "every value" for that field.

Use */5 * * * *. The */5 in the minute field means "every value divisible by 5" — so the job fires at :00, :05, :10 and so on, every hour of every day.

minute · hour · day-of-month · month · day-of-week. For example, 0 9 * * 1-5 runs at 09:00 on Monday through Friday, and 0 0 1 * * runs at midnight on the first of every month.

Yes — this tool expands @hourly, @daily, @midnight, @weekly, @monthly and @yearly to their five-field equivalents. @reboot is the exception: it runs once at boot, so there is no schedule to predict — which also makes it a prime candidate for heartbeat monitoring, since nothing tells you it stopped running.

Cron has no built-in alerting. When a job crashes, hangs, or simply stops being scheduled (a server migration, a commented-out line, a full disk), the only default signal is an email to the local Unix mailbox that nobody reads. The job just… stops, and you find out when the backups are missing.

Instead of watching for failures, your job pings a unique URL after every successful run. A monitor expects that ping on schedule — if it doesn’t arrive within the expected interval plus a grace period, the silence itself raises an alert and pages a human. It catches every failure mode at once: crashes, hangs, missing schedules, dead servers.

Big enough to absorb the job’s own runtime plus scheduler jitter, small enough that a real failure still pages you promptly. A solid rule of thumb — and what this calculator recommends — is max(10 minutes, 25% of the interval between runs).

No. The parsing, translation, and schedule calculation all run in your browser. Nothing you type here leaves the page.