Cron Expression Builder
Developer
Pick a frequency (every minute / hour / day / week / month / custom) and the tool generates the 5-field cron expression for you, with a plain-language description that always matches. Custom mode exposes all five fields if you need fine-grained control. The output is standard POSIX cron — works with crontab, GitHub Actions, Vercel Cron, Cloudflare Cron Triggers, and most schedulers.
0 9 * * *
Plain language: Every day at 09:00
How to use
- Pick a frequency.
- For 'every day' / 'every week' / 'every month', set the hour, minute, weekday, or day-of-month.
- For totally custom schedules, switch to Custom and edit each field directly.
- Copy the cron expression.
Frequently asked questions
- Which cron syntax is this?
- Standard 5-field POSIX cron — minute, hour, day-of-month, month, day-of-week. The same format used by crontab and most modern serverless schedulers.
- Can I express 'every Monday and Wednesday at 9am'?
- Yes — switch to Custom and set day-of-week to '1,3'. The Cron Explainer tool will translate it back into 'At 09:00 on Monday and Wednesday' so you can sanity-check.
- Why is day-of-month / day-of-week confusing together?
- In standard cron these are OR'd: '0 9 1 * 1' means 1st of the month OR every Monday at 9. Most schedulers honor this rule; a few quirky ones don't. Test in your target system.
- What about seconds?
- Standard cron doesn't have a seconds field — its smallest grain is one minute. For second-level granularity you'd use Quartz cron (6/7 fields), which this tool doesn't generate.
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