PrimeUtil

Cron Expression Validator & Builder

Validate standard 5-field Unix cron strings, get a plain-English schedule description, and preview the next 10 run times. Use the visual builder for common patterns (every N minutes, hourly, daily, weekdays, weekends, weekly, monthly) or browse grouped examples inspired by crontab-style cheat sheets. Field-by-field breakdown and copy-to-clipboard included.

Type a standard 5-field cron string (minute hour day month weekday). Invalid syntax is highlighted; valid schedules show plain English and next run times.

0

Minute

9

Hour

*

Day

*

Month

1-5

Weekday

In plain English

At 9:00 AM, on Monday through Friday

Next 10 run times

#1Tue, Jun 9, 202609:00 AM
#2Wed, Jun 10, 202609:00 AM
#3Thu, Jun 11, 202609:00 AM
#4Fri, Jun 12, 202609:00 AM
#5Mon, Jun 15, 202609:00 AM
#6Tue, Jun 16, 202609:00 AM
#7Wed, Jun 17, 202609:00 AM
#8Thu, Jun 18, 202609:00 AM
#9Fri, Jun 19, 202609:00 AM
#10Mon, Jun 22, 202609:00 AM

Field order (Unix cron)

minute · hour · day-of-month · month · day-of-week — same style as crontab.guru and their examples.

SymbolMeaningExample
*Any value* in minute = every minute
,List1,15,30 = at 1, 15, and 30
-Range1-5 = Monday through Friday (weekday field)
/Step*/15 = every 15 units; 0-20/5 = steps of 5 in range

Features

  • Syntax validation with clear error messages
  • Visual schedule builder for common cron patterns
  • Grouped example library (minutes, hours, daily, weekly, monthly)
  • Human-readable description and next 10 run times
  • Field-by-field breakdown and one-click copy

Frequently Asked Questions

What is a cron expression?
A cron expression is a string of 5 fields defining a recurring schedule: minute, hour, day of month, month, and day of week. They are used in Unix cron jobs, GitHub Actions, AWS Lambda, Kubernetes CronJobs, and many other schedulers.
What does * mean in a cron expression?
An asterisk (*) means 'every possible value' for that field. For example, * in the minute field means 'every minute', and * in the month field means 'every month'.
What does 0 9 * * 1-5 mean?
This runs at 09:00 on every weekday (Monday through Friday). Broken down: 0 = at minute 0, 9 = at hour 9, * = every day of month, * = every month, 1-5 = Monday through Friday.
How do I build a cron without typing all five fields?
Open the Build expression tab, pick a schedule type (for example weekdays or every 15 minutes), set the time or step values, and copy the generated string. You can switch back to Validate & explain to confirm the next run times.

From our blog

Read Cron Expressions Without Guessing: Schedules in Plain Language

Understand five-field cron syntax, common presets, and how to sanity-check next run times.

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