Cron Builder — build cron expressions from scratch

Decide the smallest cadence (minute? hour? day?), then fill in each field from left to right. Minute, hour, day-of-month, month, day-of-week. Use a wildcard `*` for any value you don't care about, a literal for a specific time, a list for a few, a range for a sequence, and a step for every Nth. CronTool's builder gives you input boxes for each field with hints, so you can click your way to the right expression.

`0 9 * * 1-5` — at 09:00 every weekday. It uses a literal (`0` minute, `9` hour), a wildcard (any day-of-month, any month), and a range (`1-5` for Mon-Fri). Read that one until it clicks, then everything else is variation on the same theme.

Use the step syntax in the minute field: `*/N * * * *`. So every 5 minutes is `*/5 * * * *`, every 10 is `*/10 * * * *`, every 15 is `*/15 * * * *`. CronTool's builder accepts step syntax in any field — use `0 */2 * * *` for every 2 hours, etc.

Combine list, range and step in the same field. `0 9-17/2 * * 1-5` runs at the top of the hour, every 2 hours from 09:00 to 17:00, on weekdays. For schedules a single cron can't express (e.g. 'every 15 min except 03:00'), use multiple cron lines — see the multi-cron visualizer.

Yes — every keystroke updates the calendar of next runs and the natural-language description below the input grid. If a field is invalid you'll see it highlighted in red with the parser error. Tweak until the calendar matches your intent.

Toggle the extended-cron switch in the top bar to enable seconds and year fields. AWS EventBridge requires `?` in either day-of-month or day-of-week — the builder warns you. Vercel uses standard 5-field syntax (UTC). Quartz uses 6-7 fields with optional seconds and year. The builder validates against the dialect you select.