Cron Expression Generator

The Cron Expression Generator builds five-field cron schedules visually and proves they work before you ship them. Each of the five fields — minute, hour, day-of-month, month, and day-of-week (0 = Sunday) — gets its own row with a mode selector: Every (*), Specific, Range (a-b), Step (*/n), or List (a,b,c), with number inputs validated against each field's legal range and month and weekday names shown as you type. Ten one-click presets cover the schedules people actually need, from Every minute through Hourly and Weekdays 8:30am to Weekends noon. The generated expression renders in a large monospace box with a live Valid/Invalid status, a plain-English description of each field, and a Copy button; below it, the Next 5 executions card computes concrete upcoming run times from your local clock using standard cron semantics, where day-of-month and day-of-week combine as OR when both are restricted. A quick-reference strip documents field order and the */n, a-b, a,b,c syntax. For crontab entries, GitHub Actions schedules, or Kubernetes CronJobs, it removes the guesswork.

1. 1

   Click a preset button (e.g. Every 15 min) to start from a known-good schedule.

2. 2

   For each of the five fields, choose a mode: Every, Specific, Range, Step, or List.

3. 3

   Fill the numeric inputs that appear for the chosen mode — the row validates the range live.

4. 4

   Copy the generated cron expression with the Copy button or download it as cron.txt.

5. 5

   Check the Next 5 executions card to confirm the schedule fires when you expect.

• Building a crontab entry without memorizing the five-field order.
• Generating GitHub Actions cron schedules for CI triggers.
• Creating Kubernetes CronJob schedules for periodic jobs.
• Verifying what a vendor-supplied cron string actually does by rebuilding it visually.
• Choosing between day-of-month and day-of-week semantics with the preview.
• Documenting a schedule with the plain-English field descriptions.

• Remember this tool emits five-field cron (no seconds); Quartz and some systems need six fields.
• Day-of-week is 0–6 with 0 = Sunday here — double-check the platform, since some systems treat 0 as Monday.
• When both day-of-month and day-of-week are restricted, cron fires when either matches (OR), which surprises people — use the preview to confirm.
• Validate the Next 5 executions against your own timezone expectations before deploying.
• Prefer step expressions like */15 over long lists for readability in stored crontabs.
• For schedules that never fire within a year (like Feb 31), the tool reports it — trust the empty-state message.

• Start from the closest preset — it fills all five fields correctly and you only tweak one or two.
• Read the plain-English description under the expression before copying; it catches wrong-field mistakes.
• Check the Next 5 executions after any change to feel the rhythm of the schedule.
• Keep day-of-month or day-of-week at * unless you have a specific reason, to avoid OR-matching surprises.