Cron Expression Parser & Explainer

The Cron Expression Parser turns any standard 5-field cron expression into plain English and previews the next ten execution times in your local timezone. It's the fast way to answer 'when does this actually run?' without spinning up a scheduler or squinting at `*/5 1-6 * * MON-FRI` for the tenth time. The parser accepts the classic Vixie-cron syntax used by Linux crond, GitHub Actions, Kubernetes CronJob, Vercel Cron, Netlify Scheduled Functions, pg_cron, Amazon EventBridge (5-field mode), and nearly every framework-level scheduler.

Under the hood the tool fully expands each field — supporting ranges (`1-5`), lists (`1,15,30`), step values (`*/10`, `0-30/5`), month and day-of-week aliases (`JAN`–`DEC`, `MON`–`SUN`), and the standard Vixie 'OR' semantics when both day-of-month and day-of-week are restricted. Invalid fields, out-of-range values, and malformed step syntax are caught with a clear per-field error rather than silently producing weird runs.

Use the parser when you write a new cron, when you inherit one you don't trust, when you need to reason about how often a job actually fires, and when you want to see whether your daylight-saving assumptions are right (all previews are rendered in your browser's local timezone). Preset chips cover the everyday patterns — every 5 minutes, hourly, daily at 3, weekdays at 9, first of month, every Sunday.