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Cron Checker (6 Fields)

Paste a 6-field cron expression (with seconds) to validate it, normalize names (JAN, MON, etc.), and preview upcoming run times in your local timezone. This checker focuses on common Quartz-style syntax: *, numbers, ranges, lists, steps, and ? for day-of-month/day-of-week.

Category: Developer · URL: /tools/cron-checker-6-fields.html
Format: sec min hour day month dow
Supported: *, numbers, lists (1,2,3), ranges (MON-FRI, 1-5), steps (*/5, 1-10/2), names (JAN, SUN), and ? (only in day-of-month or day-of-week).
Notes: Output preview uses your local timezone. If both day-of-month and day-of-week are specified (not ?), this tool treats them as OR (common cron behavior) and prints a warning. 
Ready. Paste a 6-field cron and click Check.
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Privacy: runs locally in your browser. No uploads, no tracking scripts.

How to use

Use this tool to verify a seconds-based (6-field) cron expression.

  1. Paste your cron into the input (format: sec min hour day month dow).
  2. Click Check to validate and see a normalized version.
  3. Review errors/warnings and the next run-time preview.
  4. Fix the expression and re-check until it’s valid.
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Secondary intents covered: Validate whether a 6-field cron string is syntactically correct, Find which field is invalid and why (range/step/list issues), Normalize month/day names into numeric equivalents, Confirm allowed ranges for each field (sec/min/hour/dom/month/dow), Understand how day-of-month and day-of-week interact (OR vs ?), Preview the next few run times to confirm scheduling, Quickly test common patterns like every N minutes or weekdays only, Copy a compact validation report to share in tickets or PRs

FAQ

What does “cron 6 fields” mean?

It’s a cron format that includes seconds: sec min hour day month dow. This is commonly used by Quartz-style schedulers.

Which syntax does this checker support?

*, numbers, lists, ranges, steps (e.g. */10), month/day names (JAN, MON), and ? in day-of-month/day-of-week.

Can I use ? in any field?

No. This tool only allows ? in day-of-month or day-of-week, where it means “no specific value”.

How are day-of-month and day-of-week combined?

If both are specified (not ?), this tool treats them as OR (either can match) and prints a warning because some schedulers require one side to be ?.

Does the “Next runs” preview use UTC?

The preview is calculated in your local timezone and also prints the ISO timestamp for reference.

Why does MON-FRI become 1-5?

This tool normalizes names to numbers to reduce ambiguity: Sunday=0, Monday=1, …, Saturday=6.

Does this support advanced Quartz tokens like L, W, or #?

No. It focuses on the most common cron building blocks (wildcards, lists, ranges, steps, and ?).