Tool overview
What is a Cron Parser?
A cron parser turns crontab expressions into plain-language schedules and shows upcoming run times.
Why use this Cron Parser?
Debug CI, Kubernetes, and job-scheduler expressions locally before deploying a schedule that fires at the wrong hour.
Key Features
Plain-English decode, next-run previews, expression validation, and private client-side parsing.
How to Use
Follow these steps to get accurate results from the tool interface above.
- Enter a standard 5-field cron expression: minute hour day-of-month month day-of-week.
- Paste common patterns like 0 9 * * 1-5 (weekdays at 9 AM) or */15 * * * * (every 15 minutes).
- Read the plain-English summary and the next five scheduled execution timestamps in the output blocks.
- Fix syntax errors flagged in the error banner—invalid ranges and out-of-bounds values stop parsing.
- Copy the schedule summary or pipe expressions from deployment YAML after converting with YAML ↔ JSON.
Cron Expression Technical Specifications
This parser implements standard 5-field UNIX crontab semantics with 0–59 minute/hour ranges and 1–12 month / 0–7 weekday fields.
Five-Field Crontab Array
Fields in order: minute hour day-of-month month day-of-week. Each field accepts integers, ranges (1-5), steps (*/15), lists (1,15,30), or wildcard *.
Day-of-week uses 0 or 7 for Sunday. Some platforms use MON-FRI aliases—this parser expects numeric cron, not named months or weekdays.
Next-Run Preview Algorithm
The scheduler iterates forward from the current local time, evaluating each field constraint until five matching timestamps are found. Leap seconds and DST transitions use the browser's local timezone offset—preview times may shift across daylight saving boundaries.
Expressions that never fire (e.g. conflicting day-of-month and day-of-week with AND semantics on some platforms) may return fewer than five runs—verify against your target scheduler's field combination rules (AWS EventBridge vs standard cron differ).
Parse Failure & Exception Triggers
Out-of-range values throw immediately: minute > 59, hour > 23, month > 12, or malformed step syntax like */0. Too few or too many fields (!= 5) reports invalid expression length.
Quartz 6-field cron (with seconds) and systemd calendar events are not supported—strip the seconds field or use a Quartz-specific parser for those formats.
Frequently Asked Questions
Expandable answers for common debugging bottlenecks and data privacy questions.
Related tools
Explore other related utilities that complement this tool.
Official Documentation & References
Authoritative specifications and platform documentation for this utility.