The Cron Job Parser tool converts cron schedule expressions into plain English descriptions and calculates the next scheduled run times. It helps developers understand and validate cron schedules used in task automation, job scheduling, and periodic task execution.
Features
Human-readable cron expression descriptions
Next 5 scheduled run times
Standard 5-field cron syntax support
Detailed error messages for invalid expressions
Handles complex patterns (steps, ranges, lists)
Use Cases
Schedule Validation Verify cron schedules before deploying automated tasks
Documentation Generate human-readable descriptions of cron schedules for documentation
Debugging Understand existing cron jobs and troubleshoot scheduling issues
Planning Calculate when scheduled tasks will run to plan deployments and maintenance
Cron Syntax Cron expressions use 5 fields separated by spaces:
minute hour day month day-of-week
Field Ranges Field Range Values Minute 0-59 0 = top of hour Hour 0-23 0 = midnight, 12 = noon Day 1-31 Day of month Month 1-12 1 = January, 12 = December Day of Week 0-7 0 or 7 = Sunday, 1 = Monday
Special Characters Character Meaning Example *Any value * * * * * = every minute,List separator 1,15,30 = 1st, 15th, and 30th-Range 1-5 = 1 through 5/Step */5 = every 5 units
Enter a 5-field cron expression:
This tool uses standard 5-field cron syntax. Extended formats with seconds or year fields are not supported.
Actions Default (Describe) Generate human-readable description:
At 9:00 AM, Monday through Friday
Next Runs Calculate the next 5 scheduled executions:
3/5/2026, 9:00:00 AM 3/6/2026, 9:00:00 AM 3/9/2026, 9:00:00 AM 3/10/2026, 9:00:00 AM 3/11/2026, 9:00:00 AM
Examples Weekday Morning
Every 5 Minutes
Daily Midnight
Monthly Report
Business Hours
Quarterly
Run at 9 AM on weekdays. Expression: Description: At 9:00 AM, Monday through Friday
Next Runs: 3/5/2026, 9:00:00 AM 3/6/2026, 9:00:00 AM 3/9/2026, 9:00:00 AM 3/10/2026, 9:00:00 AM 3/11/2026, 9:00:00 AM
Run every 5 minutes. Expression: Description: Next Runs: 3/4/2026, 12:05:00 PM 3/4/2026, 12:10:00 PM 3/4/2026, 12:15:00 PM 3/4/2026, 12:20:00 PM 3/4/2026, 12:25:00 PM
Run at midnight every day. Expression: Description: Next Runs: 3/5/2026, 12:00:00 AM 3/6/2026, 12:00:00 AM 3/7/2026, 12:00:00 AM 3/8/2026, 12:00:00 AM 3/9/2026, 12:00:00 AM
Run on the 1st day of each month at 8 AM. Expression: Description: At 8:00 AM, on day 1 of the month
Next Runs: 4/1/2026, 8:00:00 AM 5/1/2026, 8:00:00 AM 6/1/2026, 8:00:00 AM 7/1/2026, 8:00:00 AM 8/1/2026, 8:00:00 AM
Run every 30 minutes during business hours (9 AM - 5 PM) on weekdays. Expression: Description: At minute 0 and 30, between 9:00 AM and 5:59 PM, Monday through Friday
Next Runs: 3/5/2026, 9:00:00 AM 3/5/2026, 9:30:00 AM 3/5/2026, 10:00:00 AM 3/5/2026, 10:30:00 AM 3/5/2026, 11:00:00 AM
Run on the first day of each quarter at midnight. Expression: Description: At 12:00 AM, on day 1 of the month, only in January, April, July, and October
Next Runs: 4/1/2026, 12:00:00 AM 7/1/2026, 12:00:00 AM 10/1/2026, 12:00:00 AM 1/1/2027, 12:00:00 AM 4/1/2027, 12:00:00 AM
Implementation Details From lib/tools/engine.ts:737-752:
case 'cron-parser' : { const expr = input . trim (); if (! expr ) return { output : 'Enter a cron expression (5 fields: min hour dom mon dow)' }; try { const cronstrueMod = await import ( 'cronstrue' ); const cronstrue = cronstrueMod . default || cronstrueMod ; const description = cronstrue . toString ( expr , { throwExceptionOnParseError: true }); if ( action === 'next-runs' ) { const runs = getNextCronRuns ( expr , 5 ); return { output: runs . join ( ' \n ' ), meta: description }; } return { output: description , meta: `Expression: ${ expr } ` }; } catch (e) { return { output : e instanceof Error ? e . message : 'Invalid cron expression' }; } }
Dependencies
cronstrue : Converts cron expressions to human-readable textgetNextCronRuns() : Custom implementation calculating future run times
Common Patterns Every Minute Description: “Every minute”
Every Hour Description: “Every hour”
Every Day at Noon Description: “At 12:00 PM”
Every Sunday Description: “At 12:00 AM, only on Sunday”
First of Month Description: “At 12:00 AM, on day 1 of the month”
Every 15 Minutes Description: “Every 15 minutes”
Weekdays at 6 AM Description: “At 6:00 AM, Monday through Friday”
Weekend Nights Description: “At 10:00 PM, only on Saturday and Sunday”
Step Values Step syntax: */step or range/step
Expression Meaning */5 * * * *Every 5 minutes 0 */2 * * *Every 2 hours 0 0 */3 * *Every 3 days 0-30/10 * * * *At minutes 0, 10, 20, 30 0 9-17/2 * * *At 9, 11, 13, 15, 17
Range Expressions Expression Meaning 0-5Values 0 through 5 1-31All days of month 9-17Business hours (9 AM - 5 PM) 1-5Weekdays (Monday-Friday)
List Expressions Expression Meaning 0,15,30,45Specific minutes 1,151st and 15th of month 1,4,7,10Quarterly (Jan, Apr, Jul, Oct) 6,0Weekends (Saturday, Sunday)
Error Handling Common error messages:
Invalid Expression Invalid cron expression (need 5 fields)
Fix: Ensure you have exactly 5 fields separated by spaces.Out of Range Error: Minute value must be between 0 and 59
Fix: Check field ranges in the syntax reference.Invalid Step Error: Invalid step value
Fix: Step values must be numeric and within field range.Cron vs Crontab Standard cron (5 fields): Minute, Hour, Day, Month, DayOfWeekCrontab (6 fields): Adds a seconds field (not supported by this tool)Extended (7 fields): Adds year field (not supported by this tool)
Time Zone Handling Cron schedules run in the server’s local time zone. Next run times are displayed in your browser’s time zone. Always verify time zone settings when deploying scheduled tasks.
