About

About cronwell

A free cron expression explainer, next-run preview and cross-dialect translator — all in your browser.

Scheduling a job sounds simple until you hit the details: Is Sunday 0 or 1? Does this platform want a seconds field? Why does AWS reject my expression unless I put a “?” somewhere? cronwell takes a cron expression, explains exactly what it does, shows the next five times it will fire in any timezone, and rewrites it for Unix cron, GitHub Actions, Kubernetes CronJob, Quartz, AWS EventBridge and systemd OnCalendar.

It’s built for backend and devops engineers and indie developers wiring up scheduled jobs across more than one system. The schedule math and the dialect conversions run as pure functions in your browser — there’s no backend, no account, and nothing you type is sent anywhere.

cronwell is honest about its limits: when a conversion can’t be expressed exactly (for example, day-of-month and day-of-week together in Quartz), it tells you instead of silently producing something wrong.