Cron Expression Reader
Translate cron strings into plain English. Paste any 5- or 6-field cron expression and see exactly when it runs.
Last updated: April 2026 · Runs in your browser · No sign-up
Why this matters
Cron's terseness is a feature for typing and a bug for reading. */15 2-4 * * 1,3,5 becomes 'every 15 minutes, between 2 AM and 4 AM, on Mondays, Wednesdays and Fridays' — a lot clearer. Paste unfamiliar expressions here before editing crontabs in production.
Frequently Asked Questions
What cron syntaxes are supported?
Standard 5-field (Unix/Linux), 6-field (Quartz with seconds), and common extensions like @hourly, @daily, @weekly, @monthly, @yearly, @reboot.
Why does the preview differ from my server?
Most likely a timezone mismatch. Our preview uses your browser's timezone; your server likely uses UTC. Add the TZ= prefix or check your crontab's CRON_TZ setting.
Can it explain complex patterns like 'last Friday of month'?
Standard cron can't express 'last Friday' (that's a Quartz-only feature with 'L' and '#' specifiers). The reader flags unsupported characters with a clear error.
Does it catch common mistakes?
Yes. Typical errors: wrong field count, out-of-range values (hour 24), stepping that doesn't divide the range cleanly. Each is flagged with the position in the string.