Cron Expressions

cronbase uses standard 5-field cron expressions, the same format used by crontab.

Format

┌───────────── minute (0-59)
│ ┌───────────── hour (0-23)
│ │ ┌───────────── day of month (1-31)
│ │ │ ┌───────────── month (1-12)
│ │ │ │ ┌───────────── day of week (0-6, Sun=0)
│ │ │ │ │
* * * * *

Special characters

Character	Description	Example
*	Any value	* * * * * (every minute)
,	List	1,15,30 * * * * (minutes 1, 15, 30)
-	Range	1-5 * * * * (minutes 1 through 5)
/	Step	*/15 * * * * (every 15 minutes)

Named values

Months and days of week accept names (case-insensitive):

• Months: jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec
• Days: sun, mon, tue, wed, thu, fri, sat

0 9 * * mon-fri    # Weekdays at 9 AM
0 0 1 jan,jul *    # Midnight on Jan 1 and Jul 1

Presets

Preset	Equivalent	Description
@yearly	0 0 1 1 *	Once a year (midnight, Jan 1)
@annually	0 0 1 1 *	Same as @yearly
@monthly	0 0 1 * *	First of every month
@weekly	0 0 * * 0	Every Sunday at midnight
@daily	0 0 * * *	Every day at midnight
@midnight	0 0 * * *	Same as @daily
@hourly	0 * * * *	Top of every hour

Examples

Expression	Description
*/5 * * * *	Every 5 minutes
0 * * * *	Top of every hour
0 2 * * *	Daily at 2:00 AM
30 9 * * 1-5	Weekdays at 9:30 AM
0 0 * * 0	Every Sunday at midnight
0 0 1 * *	First of every month at midnight
0 6,18 * * *	Twice daily at 6 AM and 6 PM
0 0 1 1 *	Once a year on January 1
0 */4 * * *	Every 4 hours
15 2 1,15 * *	2:15 AM on the 1st and 15th

Validation

Use the CLI or API to validate expressions:

# API endpoint
curl "http://localhost:7433/api/cron/describe?expr=0+2+*+*+*"

{
  "valid": true,
  "description": "at minute 0, at hour 2",
  "nextRun": "2025-01-16T02:00:00.000Z"
}