Cron Expression Parser Developer
Explain a cron schedule in plain English and preview the next run times.
Cron Expression Parser is a free online tool that explain a cron schedule in plain English and preview the next run times. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free — no account, no quota, no watermark
- Category
- Developer
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- 1
- Works offline
- Yes, after the first visit
About Cron Expression Parser
A cron expression is translated into plain English so you can check it before it runs at the wrong time for a month. The rule that catches nearly everyone: when both day-of-month and day-of-week are restricted, cron ORs them rather than ANDing them. `0 0 1 * 1` runs on the 1st of the month **and** every Monday — not on Mondays that fall on the 1st.
How to use it
- Enter cron expression.
- Results update the moment anything changes.
The one setting
| Setting | What it does | Default |
|---|---|---|
| Cron expression | For example: min hour dom mon dow | 0 9 * * 1-5 |
Under the hood
| Runs on | plain JavaScript — runs the whole thing |
| Controls | Cron expression |
Questions
What do the five fields mean?
Minute (0–59), hour (0–23), day of month (1–31), month (1–12), day of week (0–7, where both 0 and 7 are Sunday). Some systems add a sixth leading field for seconds.
Why did my job run more often than expected?
Almost certainly the day-of-month/day-of-week OR rule. Restrict only one of the two fields and leave the other as `*`.