Cron Parser

Cron expressions are terse and easy to get wrong. Paste one and see what it means in plain English, field by field, along with the next scheduled run times so you can sanity-check the schedule before deploying it.

Standard 5-field expressions are supported, including ranges (1-5), lists (1,15), steps (*/10), names (MON, JAN), and shortcuts like @daily and @hourly.

Common uses

• Verify a crontab entry runs when you think it does
• Understand a schedule someone else wrote
• Check how a step expression like */15 actually behaves

Example

*/15 9-17 * * 1-5

Every 15 minutes, between 09:00 and 17:59, Monday through Friday.

Limitations

• Next runs are computed in your local timezone; servers often run cron in UTC
• Six-field (seconds) and Quartz-specific syntax (?, L, W, #) are not supported

Is my cron expression sent anywhere when I parse it?

No. The expression is parsed by JavaScript running in your browser, and nothing is transmitted or stored — job schedules that hint at your infrastructure never leave your device.

What do the five fields in a cron expression mean?

In order: 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 mean Sunday). A * in a field means every value, so * * * * * runs every minute.

What does */15 mean in cron?

It is a step value: starting from the field's minimum, every 15th value matches. In the minute field, */15 runs at minutes 0, 15, 30, and 45 of each matching hour.

Why doesn't my cron job run at the time this tool shows?

The next run times here are computed in your local timezone, but servers commonly run cron in UTC. Check the server's timezone (the TZ variable or /etc/timezone) and shift the hour field accordingly.

Does this parser support shortcuts like @daily and @reboot?

@hourly, @daily, @weekly, @monthly, @yearly, and @annually are expanded to their 5-field equivalents (for example @daily becomes 0 0 * * *). @reboot is recognized but has no schedule to explain — it runs once at system startup.