Why this matters
Invalid cron schedules cause missed jobs or job storms. Previewing schedules prevents operational incidents.
What this tool does
Build and validate 5-field cron expressions, then preview the next deterministic run times from an optional anchor timestamp.
Calculation model
Each field is parsed for wildcards, lists, ranges, and steps. Next-run generation scans minute-by-minute and records the first matching occurrences.
Result interpretation
Use warnings for ambiguous schedules (especially day-of-month plus day-of-week combinations), and verify horizon previews before deploying jobs.
Limits and validation
This tool targets standard 5-field cron syntax. Quartz 6/7-field extensions are out of scope in this phase.
Use Cases
- Validate data formats quickly while debugging APIs and integrations.
- Confirm hardware and viewport behavior during QA checks.
- Reduce context-switching by running diagnostics directly in the browser.
Frequently Asked Questions
Which cron format is supported?
Standard 5-field format: minute hour day-of-month month day-of-week.
Can I preview next runs before deployment?
Yes. The tool generates upcoming run timestamps using the validated expression and horizon size.
Does this support Quartz 6/7-field syntax?
No, this phase is intentionally limited to standard 5-field cron expressions.
Why do I see a warning when both DOM and DOW are set?
Cron implementations differ in how these fields interact. The warning reminds you to verify scheduler-specific semantics.
Can I start from a custom anchor time?
Yes. Provide an optional ISO-like anchor datetime to make previews reproducible.
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