Expression Validator
Validate cron expressions and catch edge cases before they cause problems.
What It Does
Next Run Preview
See the next 10 (or more) scheduled run times for your expression. No more guessing when your job will actually fire.
Timezone Support
Preview runs in any timezone. Verify your job runs at the right time for your users, regardless of server location.
Edge Case Warnings
Get automatic warnings for common pitfalls like February 29th, day 31 schedules, DST transitions, and more.
Shareable Links
Generate a URL for any expression to share with your team or save for later.
Edge Case Warnings
The validator automatically detects these common issues:
Day 31 schedules
0 0 31 * * — Only runs in months with 31 days (Jan, Mar, May, Jul, Aug, Oct, Dec). Skipped in Feb, Apr, Jun, Sep, Nov.
February 29th
0 0 29 2 * — Only runs during leap years. Your job will execute roughly once every 4 years.
Day + Weekday combination
0 0 15 * 1 — When both day-of-month AND day-of-week are specified, cron runs when EITHER matches (OR logic, not AND).
Every minute
* * * * * — Running every minute can be expensive and may indicate a misconfiguration. Consider if this frequency is necessary.
Cron Syntax Reference
| Field | Values | Special Characters |
|---|---|---|
| Minute | 0-59 | * , - / |
| Hour | 0-23 | * , - / |
| Day of Month | 1-31 | * , - / |
| Month | 1-12 | * , - / |
| Day of Week | 0-6 (Sun-Sat) | * , - / |
Common Examples
* * * * *Every minute0 * * * *Every hour0 0 * * *Every day at midnight0 9 * * 1-5Every weekday at 9am0 0 * * 0Every Sunday at midnight0 0 1 * *First day of every month*/15 * * * *Every 15 minutes0 9,17 * * *At 9am and 5pm daily0 0 1 1 *Every January 1st at midnight