The Locolory toolkit / DevOps & Systems
Build, parse, and debug five-field cron expressions and seconds-first six-field schedules with human-readable translations and next-run previews.
What is a cron expression? A traditional cron expression has five space-separated schedule fields: minute (0–59), hour (0–23), day of month (1–31), month (1–12), and day of week (0–7, with 0 or 7 commonly Sunday).
Pure client-side syntax evaluation. Confirm the dialect, timezone, and DST behavior of the scheduler that will execute the job.
*/15 9-17 * * 1-5
every 15 minutes, during hour 9-17, on weekdays (browser local time).
Traditional crontab uses five schedule fields; the following text is the shell command, not a seconds field. This tool's six-field mode is explicitly seconds-first.
* means all values, commas create lists, hyphens create inclusive ranges, and slashes create steps. ?, L, W, and # are Quartz-style extensions and are intentionally rejected by the portable preview.
| Expression | Meaning |
|---|---|
| * * * * * | Every minute |
| */5 * * * * | Every 5 minutes |
| */15 9-17 * * 1-5 | Every 15 minutes during weekday work hours |
| 0 * * * * | Hourly |
| 0 */2 * * * | Every 2 hours |
| 0 0 * * * | Daily at midnight |
| 0 6 * * * | Daily at 6 AM |
| 30 8 * * * | Daily at 8:30 AM |
| 0 0,12 * * * | Twice daily |
| 0 9 * * 1 | Monday at 9 AM |
| 0 9 * * 1-5 | Weekdays at 9 AM |
| 0 10 * * 0,6 | Weekends at 10 AM |
| 0 0 1 * * | First of each month |
| 0 0 15 * * | Fifteenth of each month |
| 0 0 1 1 * | Every January 1 |
| 0 0 * * 0 | Every Sunday |
| 0 18 * * 5 | Friday at 6 PM |
| 0 9 1,15 * * | First and fifteenth at 9 AM |
| 0 0 1 */3 * | First day of every third month |
| 0 23 28-31 * * | At 11 PM on days 28–31 |
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In traditional crontab syntax, 0 represents Sunday and many implementations also accept 7 as Sunday. Quartz uses a different day numbering convention, so always verify the scheduler dialect.
A traditional five-field expression such as */15 9-17 * * 1-5 runs at minutes 0, 15, 30 and 45 during hours 9 through 17, Monday through Friday. The 17 hour includes runs through 17:45.
Traditional user crontab uses five schedule fields followed by a command. Quartz places seconds first, commonly has six or seven schedule fields, uses ? to leave a day field unspecified, and supports extensions such as L, W and #.
Check the daemon and service status, installed crontab, user permissions, environment and PATH, timezone, command quoting, logs, and daylight-saving transitions. Missing wall-clock times may never run and repeated times may run twice.