Build cron expressions visually, parse existing ones, and see next run times.
0 * * * *Every hour
| Field | Allowed Values | Special Characters |
|---|---|---|
| Minute | 0-59 | * , - / |
| Hour | 0-23 | * , - / |
| Day of Month | 1-31 | * , - / |
| Month | 1-12 | * , - / |
| Day of Week | 0-7 (0 and 7 = Sun) | * , - / |
*Any value
* * * * * = Every minute
,Value list separator
1,15 * * * * = At minute 1 and 15
-Range of values
1-5 * * * * = Minutes 1 through 5
/Step values
*/15 * * * * = Every 15 minutes
Cron is a time-based job scheduler found in Unix and Linux operating systems. A cron expression is a compact string of five fields that defines when a scheduled task should execute. The format was originally created for the cron daemon in Unix Version 7, released in 1979.
Today, cron syntax is used far beyond traditional crontab. It powers scheduled workflows in GitHub Actions, Kubernetes CronJobs, AWS CloudWatch Events, Google Cloud Scheduler, and virtually every modern CI/CD and cloud platform. Understanding cron expressions is an essential skill for DevOps engineers and backend developers.
Task Scheduling
Schedule recurring jobs on Linux/Unix servers with crontab
CI/CD Pipelines
Set up scheduled builds and deployments in GitHub Actions, GitLab CI, etc.
Backup Automation
Automate database and file backups at specific intervals
Server Maintenance
Schedule log rotation, cache clearing, and system health checks
What is a cron expression?
A cron expression is a string of five fields separated by spaces that represents a schedule. The five fields are: minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-7, where 0 and 7 are Sunday). Cron is used on Unix/Linux systems to schedule recurring tasks.
What do the special characters in cron mean?
The asterisk (*) means "every" value for that field. The comma (,) separates multiple values (e.g., 1,3,5). The hyphen (-) defines a range (e.g., 1-5 for Monday through Friday). The slash (/) specifies step values (e.g., */15 means every 15 units).
How do I schedule a cron job to run every 5 minutes?
Use the expression */5 * * * *. The */5 in the minute field means "every 5 minutes". The asterisks in the remaining fields mean it runs every hour, every day, every month, and every day of the week.
What is the difference between day of month and day of week in cron?
Day of month (field 3) specifies which calendar date(s) the job runs on (1-31). Day of week (field 5) specifies which weekday(s) the job runs on (0-7, where 0 and 7 both represent Sunday). When both are set to specific values (not *), most cron implementations run the job when either condition is met.
Can I use this cron builder for GitHub Actions or Kubernetes?
Yes! The standard 5-field cron syntax generated by this tool works with crontab on Linux/Unix, GitHub Actions scheduled workflows, Kubernetes CronJobs, AWS CloudWatch Events, Google Cloud Scheduler, and most other scheduling systems.
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