Cron Expression Builder
Standard 5-field cron: minute, hour, day of month, month, weekday. Names like JAN or FRI work too. Parsed entirely in your browser.
How it works
仕組みCron expressions are terse five-field schedules (minute, hour, day of month, month, weekday), and one misplaced asterisk can mean a job firing at midnight instead of noon. This builder reads any standard 5-field expression and translates it into plain English, so you can confirm “0 9 * * 1-5” really means weekdays at 09:00 before it lands in a crontab or CI config. Preset chips cover the common schedules, each field gets its own labeled reading, and everything is parsed instantly in your browser with clear errors for invalid syntax.
Both, in most implementations: vixie-cron and Linux crontab accept either, and this tool follows suit. Names like SUN, MON, or JAN also work. If you’re targeting a specific runner (Jenkins, GitHub Actions, Quartz), double-check its docs, since a few dialects differ.
In classic cron the two are OR-ed, not AND-ed: “0 0 1 * MON” runs on the 1st of every month and on every Monday. This trips people up constantly, so the plain-English reading here spells out both conditions.
Standard Unix cron uses exactly five fields. Six- and seven-field variants (with seconds or years) exist in Quartz and some cloud schedulers, but they’re dialects, not the baseline. If your target system shows six fields, the first one is usually seconds, and the remaining five read the same way as here.