cron expression · plain english
Run a cron job every 15 minutes
Fires at HH:00, HH:15, HH:30, HH:45 — exactly 4 times per hour. Standard cadence for batch jobs that need quarter-hour responsiveness.
beginner
POSIX / Jenkins / Quartz / AWS
*/15 * * * *
run a cron job every 15 minutes.
Next 5 fire times
Computed live in your local timezone. The cron expression itself is timezone-agnostic — these times reflect your browser clock.
Cross-system syntax variants
Same intent, different schedulers. Use this table when migrating between systems.
| System | Expression | Note |
|---|---|---|
| Standard cron (POSIX) | */15 * * * * | step notation, predictable quarter-past timing |
| Cron (verbose alt) | 0,15,30,45 * * * * | explicit list — equivalent, sometimes preferred for readability |
| Jenkins | H/15 * * * * | consider H/15 to avoid all jobs firing simultaneously at :00 |
| Quartz (Java) | 0 0/15 * * * ? | 6-field — start at minute 0, step 15 |
| AWS EventBridge | rate(15 minutes) | or cron(0/15 * * * ? *) for minute-aligned |
Common pitfalls
- Quarter-past cadence overlaps with `*/5`, `*/10`, `*/30` — on busy hosts you get a 4-job spike at HH:00. Stagger.
- Some apps expect HH:15-aligned data drops (financial feeds). Check your downstream contract before changing offset.
- If you switch from cron to systemd timer, `OnCalendar=*:0/15` produces identical schedule — but `OnUnitActiveSec=15min` does NOT (relative timing).
Use cases
- Webhook retry processor for failed deliveries
- Search index incremental refresh
- Currency rate refresh from FX provider
- Stale session cleanup
- Dashboard aggregate refresh
Translate any cron expression
cronwtf takes any cron string and returns plain-English description plus the next 5 fire times in your timezone. Standard 5-field, Jenkins H, Quartz 6-field — all supported.
Open cronwtf
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