03 / DEVELOPER
Cron Builder
Read and write 5-field POSIX or 6-field Quartz cron expressions, see a plain-language description and preview the next five fire times.
How to use
- 1Type or paste a cron expression. Both 5-field POSIX (e.g. `30 9 * * 1-5`) and 6-field Quartz-style (with seconds) are accepted.
- 2Switch the Fields control to match the format your scheduler expects.
- 3Read the human-readable description to sanity-check the schedule.
- 4The Next 5 runs panel shows when the schedule will fire next, in your local timezone.
Frequently asked questions
Which cron flavor is this?
5-field is the POSIX cron used by Linux, Vercel, GitHub Actions and most Unix schedulers. 6-field adds a leading seconds field, matching Spring/Quartz and Kubernetes' Quartz-compatible runtimes.
Are special strings like @daily supported?
Yes — @yearly, @annually, @monthly, @weekly, @daily and @hourly are accepted and translated for both the description and next-run preview.
Why are the next-run timestamps in my local time?
Most users want to confirm 'will this run when I expect?' That answer depends on your timezone, not UTC. We label the panel accordingly so you don't conflate the two.
Does this support */N step values and L (last) tokens?
Step values and ranges (e.g. `*/15`, `1-5`) work in both modes. The 'L' (last) and 'W' (weekday) tokens are Quartz-specific and only accepted in 6-field mode.
Is anything saved or sent to a server?
No. Both the description and the next-run preview run locally; the cron parser library loads on first visit.