Cron Builder
Describe a schedule in plain English — "every weekday at 9am", "every 15 minutes", "daily at 06:00" — or paste an existing cron expression, and get the built expression in your chosen platform dialect (Unix, Quartz / Spring, GitHub Actions, Vercel, AWS EventBridge, Kubernetes, generic 5/6-field). The Next-runs / Platforms / Examples tabs show a live preview, every platform variant, and phrase examples. Runs in your browser; nothing is uploaded.
Auto-builds as you type. Ctrl+Enter to re-run.
How to use the Cron Expression Builder
Build cron schedules visually for the platforms developers actually use — Unix / Linux cron (5-field), Quartz / Spring Scheduler (6-field with seconds), GitHub Actions (5-field UTC), AWS EventBridge / CloudWatch (6-field with year, no day-of-week + day-of-month together), and Kubernetes CronJob. Pick minute, hour, day, month, weekday, and see the next 10 run times instantly to confirm the schedule. Runs locally in your browser.
What it does
- Visual builders for minute, hour, day-of-month, month, day-of-week, and (when used) seconds, year.
- Live preview of the cron expression and the next 10 run times in UTC and local time.
- Format presets: Unix, Quartz/Spring, GitHub Actions, AWS EventBridge, Kubernetes CronJob.
- Common-schedule shortcuts: every minute, hourly, daily 6am, weekday 9am, weekly Monday, monthly first.
- Plain-English description of what the expression means.
- Detects expressions that will never run (e.g., Feb 30).
When to use it
- Schedule a daily report at 06:00 UTC, weekdays only.
- Configure a GitHub Actions
on: scheduletrigger and verify the timing. - Build an AWS EventBridge cron rule for a Lambda function.
- Define a Kubernetes
CronJobschedule. - Decode an existing cron string you inherited from a runbook.
- Compare a Quartz 6-field schedule to a Unix 5-field equivalent.
How to use it
- Pick the target platform (Unix, Quartz, GitHub Actions, EventBridge, Kubernetes).
- Set each field via the visual builder or pick a preset.
- Watch the generated cron expression and the next run times update live.
- If you already have a cron string, paste it into the analyzer to decode and preview.
- Copy the expression into your scheduler / manifest / workflow.
- Pair with the Cron Analyzer to debug an existing expression in detail.
Tips & pitfalls
- Time zone: GitHub Actions and AWS EventBridge run in UTC. Convert from your local time before saving.
- AWS EventBridge cron has six fields including
year, and you cannot use both day-of-month and day-of-week — one must be?. - Quartz / Spring uses six fields including seconds at the start.
- Day-of-month and day-of-week behave differently across schedulers — always verify with the next-run preview.
- Avoid
* * * * *(every minute) on shared infrastructure unless you're confident the job is idempotent. - Use
@reboot/@dailyshortcuts only on platforms that support them — they are not portable.
FAQ
- How do I schedule a job for every weekday at 9am?
0 9 * * 1-5for Unix / GitHub Actions. The builder produces this for you. - What is the difference between Unix cron and Quartz cron? Unix is 5 fields starting at minute. Quartz is 6 fields starting at seconds and has additional features (
L,W,#). - How do I write AWS EventBridge cron? 6 fields ending in year, with
?in either day-of-month or day-of-week. The builder emits the right shape automatically. - What time zone does cron use? Unix cron uses the system timezone; most cloud schedulers default to UTC. Always check.
- Is my expression uploaded? No. All calculation runs in your browser.
- How do I decode an existing cron string? Use the Cron Analyzer for a detailed breakdown with run-time preview.
- How do I generate a cron expression? Pick a platform (Unix, Quartz, AWS EventBridge, GitHub Actions, Kubernetes) and build the schedule with the guided fields. The cron expression and the next run times update live.
Runs locally in your browser. No uploads. Always verify with the next-run preview before saving a production schedule.