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Cron Expression Builder & Explainer

Build a cron schedule with a step-by-step picker — every N minutes, hourly, daily, weekly, monthly, or yearly — and watch the expression, plain-English explanation, and next runs update live. Paste an existing cron to drive the builder in reverse, or switch to advanced mode for Quartz L/W/# specials. Copy the result as a crontab line, Kubernetes CronJob, Spring @Scheduled, AWS EventBridge cron(...), or GitHub Actions schedule.

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Tool Summary Answer Block

This tool accepts structured input and returns deterministic output in the browser with no server upload.

Tool name
Cron Expression Builder & Explainer
Input intent
Provide source content to transform, validate, or analyze.
Output intent
Receive normalized output suitable for copy, reuse, or debugging.
Example input
*/15 9-17 * * 1-5
Example output
Runs every 15 minutes past hour 9-17 on Monday, Tuesday, Wednesday, Thursday, Friday.

This expression uses syntax the builder can't represent (Quartz specials, seconds, step lists). Edit the raw expression below — the explainer and preview still work.

Runs every 15 minutes past hour 9, 10, 11, 12, 13, 14, 15, 16, 17 on Monday, Tuesday, Wednesday, Thursday, Friday.
Minute*/15
Hour9-17
Day (month)*
Month*
Day (week)1-5

Next 10 runs (UTC)

  • Thu, Jun 11, 2026, 09:00:00in 5h
  • Thu, Jun 11, 2026, 09:15:00in 5h
  • Thu, Jun 11, 2026, 09:30:00in 5h
  • Thu, Jun 11, 2026, 09:45:00in 6h
  • Thu, Jun 11, 2026, 10:00:00in 6h
  • Thu, Jun 11, 2026, 10:15:00in 6h
  • Thu, Jun 11, 2026, 10:30:00in 6h
  • Thu, Jun 11, 2026, 10:45:00in 7h
  • Thu, Jun 11, 2026, 11:00:00in 7h
  • Thu, Jun 11, 2026, 11:15:00in 7h
*/15 9-17 * * 1-5 /path/to/command
Cron syntax cheatsheet
┌── minute (0-59)
│ ┌── hour (0-23)
│ │ ┌── day of month (1-31)
│ │ │ ┌── month (1-12 or JAN-DEC)
│ │ │ │ ┌── day of week (0-6 or SUN-SAT; 7 also = Sunday)
│ │ │ │ │
* * * * *
  • * — every value
  • , — list (e.g. 1,15,30)
  • - — range (e.g. 9-17)
  • / — step (e.g. */15)
  • Aliases: @yearly, @monthly, @weekly, @daily, @hourly
  • Quartz extras (mode = Quartz): L last, LW last weekday, 15W nearest weekday, 6#2 2nd Friday, ? no-specific-value

Tool Introduction

Build a cron schedule with a step-by-step picker — every N minutes, hourly, daily, weekly, monthly, or yearly — and watch the expression, plain-English explanation, and next runs update live. Paste an existing cron to drive the builder in reverse, or switch to advanced mode for Quartz L/W/# specials. Copy the result as a crontab line, Kubernetes CronJob, Spring @Scheduled, AWS EventBridge cron(...), or GitHub Actions schedule.

Tool Overview

Cron expressions look intimidating but break down into a small set of fields. Standard (Unix) cron uses 5: minute, hour, day-of-month, month, and day-of-week. The 6-field dialect (Spring, AWS EventBridge in seconds mode) prepends a seconds field. Quartz adds a year field plus L (last), W (nearest weekday), and # (nth weekday) for more expressive calendar rules. Each field accepts numbers, ranges (1-5), lists (1,15,30), wildcards (*), step syntax (*/5), and named tokens like JAN-DEC or MON-FRI. This tool wraps that surface area in a builder for the common cases, falls back gracefully to a raw editor for advanced syntax, and always shows the parsed dialect, the upcoming runs in your chosen IANA timezone, and ready-to-paste snippets for the most common runtimes.

Use Cases

  • Use Cron Expression Builder & Explainer when you need fast build cron schedules with a step-by-step picker, then read the plain-english explanation, the next runs in any iana timezone, and ready-to-paste snippets for crontab, kubernetes cronjob, spring @scheduled, aws eventbridge, and github actions. standard, 6-field, and quartz dialects (with l, w, # specials) all supported.
  • Handle developer workflows directly in the browser with no install required.
  • Support SEO long-tail intent by covering quick checks, troubleshooting, and one-off conversions.

Input/Output Examples

Input Intent
*/15 9-17 * * 1-5
Output Intent
Runs every 15 minutes past hour 9-17 on Monday, Tuesday, Wednesday, Thursday, Friday.
Input Intent
@daily
Output Intent
Runs at minute 0 past hour 0.
Input Intent
0 0 0 L * ?
Output Intent
Quartz: runs at midnight on the last day of every month.
Input Intent
0 0 12 ? * FRI#2
Output Intent
Quartz: runs at noon on the second Friday of every month.

FAQ

Which cron dialects are supported?+
Three: classic 5-field POSIX (Unix crontab), 6-field with seconds (Spring's @Scheduled, AWS EventBridge seconds mode), and Quartz with optional 7th year field plus L, LW, W, #, and ? specials.
Are the next runs in UTC or local time?+
Whichever timezone you pick. The tool starts in your browser's local zone but accepts any IANA tz name — common picks are pre-filled in the dropdown.
How does day-of-month interact with day-of-week?+
In standard cron, when both fields are restricted the schedule fires if EITHER matches (POSIX 'OR' semantics). In Quartz one of the two must be ? since both restrictions wouldn't make sense together.
Can I use JAN-DEC or MON-FRI instead of numbers?+
Yes. Named tokens are accepted (case-insensitive) for month and day-of-week in every dialect.
What's the difference between 0-6 and 1-7 for day-of-week?+
Standard cron uses 0-6 with 0 = Sunday (7 is also accepted as Sunday for compatibility). Quartz uses 1-7 with 1 = Sunday. The tool applies the right convention based on the selected dialect.
What do L, LW, W, and # mean (Quartz only)?+
L = last day of month, LW = last weekday of month, 15W = nearest weekday to the 15th, 6#2 (or FRI#2) = second Friday of the month. ? in either day-of-month or day-of-week means 'no specific value' and is required when the other is restricted.

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