Compare Two CRON Expressions
Spot the differences between two CRON expressions. Our tool compares each field side-by-side and explains how the schedules differ. Useful for debugging or modifying cron jobs.
Expression A
0At 0
Expression B
0At 0
Expression A
9At 9
Expression B
10At 10
Expression A
*Every day
Expression B
*Every day
Expression A
*Every month
Expression B
*Every month
Expression A
1-5Weekdays (Mon-Fri)
Expression B
1-5Weekdays (Mon-Fri)
These expressions do not have overlapping execution times. The tasks will run at different times.
ASchedule A
at 9 AM on weekdays
BSchedule B
at 10 AM on weekdays
How the CRON Difference Checker Works
This tool compares two CRON expressions side-by-side and identifies exactly where they differ. It breaks down each of the five fields and shows whether the schedules overlap, conflict, or run at completely different times.
Comparison Analysis
- Enter two CRON expressions to compare
- Each field (minute, hour, day, month, weekday) is parsed and compared
- The tool generates a 24-hour timeline showing when each expression executes
- Overlapping execution times are highlighted
- A summary explains whether the expressions are identical, different, or partially overlapping
Specific Use Cases
Migrating Scheduled Jobs
A DevOps engineer is moving from Jenkins to GitHub Actions and needs to verify the new schedule matches the old one exactly.
Debugging Duplicate Runs
A developer notices their backup script runs twice on some days. They compare the two cron entries to find the overlap.
Coordinating Multiple Services
A system administrator manages cron jobs across three servers and needs to ensure they don't all hit the database simultaneously.
Code Review for Schedule Changes
During a PR review, a teammate changes a cron schedule from "0 9 * * 1-5" to "0 10 * * 1-5". The reviewer uses this tool to confirm the one-hour shift.
Audit Compliance Checks
An auditor needs to verify that security scans run at different times than backup jobs to avoid resource contention.
What to Know Before Using This Tool
Understanding the comparison results helps you make better scheduling decisions:
- Identical expressions will show "no difference" across all fields
- Expressions with different fields may still overlap (e.g., "0 9 * * *" and "0 9 * * 1-5" overlap on weekdays)
- The 24-hour timeline only shows hour-level granularity, not minute-level
- Complex expressions with lists (1,3,5) or ranges (1-5) are fully parsed
- Step values (*/15) are expanded for comparison
Frequently Asked Questions
What does "overlapping execution times" mean?
Two CRON expressions overlap when they both trigger at the same time. For example, "0 9 * * *" (daily at 9 AM) and "0 9 * * 1-5" (weekdays at 9 AM) overlap every weekday at 9 AM.
Can this compare expressions with different field counts?
No, both expressions must use the same format (standard 5-field CRON). Six-field expressions with seconds aren't supported.
How accurate is the overlap detection?
The tool analyzes the hour field to determine overlaps. For minute-level precision, you'll need to manually check expressions that share the same hours.
What if one expression uses "*" and the other uses specific values?
The tool will show them as different and indicate that the "*" expression encompasses the specific one. For example, "* 9 * * *" runs every minute from 9:00-9:59, overlapping with "30 9 * * *" at 9:30.
Can I compare more than two expressions at once?
This tool compares two expressions at a time. For multiple comparisons, run separate comparisons or use a scheduling visualization tool.
CRON Field Reference
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