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No more cron syntax confusion

Build & UnderstandCron Expressions

Create cron schedules visually, see explanations in plain English, and preview the next 10 execution times. Works with Linux, Kubernetes, GitHub Actions, AWS, and more.

Free forever. No signup required.

Cron Builder

Visual builder to create, validate, and understand cron expressions with execution preview

Open Builder
Visual Builder
Execution Preview
Validation
Plain English
100%
Browser-based
5
Cron fields supported
20+
Common presets

What is a Cron Expression?

A cron expression is a string that defines a schedule for running automated tasks. Originally from Unix/Linux, cron syntax is now the de-facto standard for job scheduling across platforms including Kubernetes CronJobs, GitHub Actions, AWS EventBridge, and virtually every CI/CD and cloud platform.

A standard cron expression has 5 fields separated by spaces, each representing a time unit. Using special characters like * (every), - (range),, (list), and / (step), you can define complex recurring schedules in a compact format.

Cron Expression Format

A standard cron expression consists of 5 fields separated by spaces. Each field accepts numbers, wildcards, ranges, and step values.

*
Minute
0-59
*
Hour
0-23
*
Day
1-31
*
Month
1-12
*
Weekday
0-7 (Sun=0,7)

Example: Run at 9 AM on weekdays

09**1-5

Meaning: At minute 0, hour 9 (9 AM), every day of the month (*), every month (*), Monday through Friday (1-5).

Cron Special Characters

*
Asterisk (Every)

Matches all possible values for the field

* = every minute/hour/etc.
,
Comma (List)

Specifies a list of values

1,15,30 = at 1, 15, and 30
-
Hyphen (Range)

Specifies a range of values

1-5 = 1, 2, 3, 4, and 5
/
Slash (Step)

Specifies step/interval values

*/5 = every 5th (0,5,10...)

Common Cron Expression Examples

ExpressionDescriptionUse Case
* * * * *Every minuteHealth checks, real-time monitoring
*/5 * * * *Every 5 minutesMetrics collection, cache refresh
*/15 * * * *Every 15 minutesData sync, API polling
0 * * * *Every hour (at minute 0)Hourly reports, cleanup tasks
0 */2 * * *Every 2 hoursBackup checks, digest emails
0 0 * * *Daily at midnightDaily backups, log rotation
0 6 * * *Daily at 6 AMMorning reports, batch processing
0 9 * * 1-5Weekdays at 9 AMBusiness notifications, standup reminders
0 0 * * 0Weekly on Sunday at midnightWeekly reports, maintenance
0 0 1 * *Monthly on the 1st at midnightMonthly billing, reports
0 0 1 1 *Yearly on Jan 1st at midnightAnnual maintenance, license renewal
0 9,17 * * *Twice daily at 9 AM and 5 PMStart/end of day summaries

Platform Compatibility

Our cron builder generates standard 5-field POSIX cron expressions compatible with these platforms:

Linux crontab

Standard 5-field POSIX cron

Kubernetes CronJob

Container scheduling

GitHub Actions

CI/CD workflow schedules

AWS EventBridge

CloudWatch Events (6-field)

Jenkins

Build automation

Azure Functions

Serverless timers

Google Cloud Scheduler

Cloud job scheduling

Vercel Cron

Edge function scheduling

Note: AWS EventBridge uses a 6-field format with an additional year field and requires ? in either day-of-month or day-of-week. Most other platforms use standard 5-field syntax.

Common Use Cases for Cron Jobs

Database Backups

Schedule daily or hourly database backups. Example: 0 2 * * * for daily at 2 AM.

Email Digests

Send daily or weekly email summaries. Example: 0 9 * * 1 for Monday 9 AM.

Data Synchronization

Sync data between systems periodically. Example: */15 * * * * for every 15 minutes.

Report Generation

Generate business reports on schedule. Example: 0 0 1 * * for monthly.

Frequently Asked Questions

How do I run a cron job every 5 minutes?

Use '*/5 * * * *'. The */5 in the minute field means every 5th minute (0, 5, 10, 15...). Similarly, use */10 for every 10 minutes, */15 for every 15 minutes, or */30 for every 30 minutes.

What does '* * * * *' mean?

It means 'every minute of every hour of every day'. Each asterisk is a wildcard meaning 'every possible value'. This is the most frequent schedule and runs 1,440 times per day.

How do I run only on weekdays?

Use '1-5' in the day-of-week field (5th field). Example: '0 9 * * 1-5' runs at 9 AM Monday through Friday. Monday is 1, Friday is 5.

Why is my cron job not running?

Common issues: 1) Syntax error - validate with our tool, 2) Wrong timezone - cron uses system time, 3) Path issues - use absolute paths in scripts, 4) Permission denied - check file permissions, 5) Conflicting day fields - day-of-month and day-of-week use OR logic.

What's the difference between Linux cron and AWS cron?

Linux uses 5 fields (minute, hour, day, month, weekday). AWS EventBridge uses 6 fields with an added year field and requires '?' in either day-of-month or day-of-week. Our builder generates standard 5-field expressions.

Can I use cron in GitHub Actions?

Yes! Use the schedule trigger: 'on: schedule: - cron: "0 9 * * 1-5"'. GitHub Actions uses UTC timezone only and supports standard 5-field cron syntax.

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Format Kubernetes CronJob manifests

Regex Tester

Test patterns for log parsing