Cron Job Parser & Explainer (Translate Cron Expressions Online)
If you manage Linux servers, CI/CD pipelines, or background Node.js task queues, you are inevitably forced to write crontab schedules. This parser takes complex cron strings (e.g. `*/15 0 1,15 * 1-5`) and translates them into an instantly readable human language description, ensuring your automated tasks trigger exactly when you intend them to.
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This tool runs completely inside your browser using client-side WebAssembly and JS. Zero data is ever sent to our servers.
Quick Examples
Syntax Reference
┌───────────── minute (0 - 59) │ ┌───────────── hour (0 - 23) │ │ ┌───────────── day of the month (1 - 31) │ │ │ ┌───────────── month (1 - 12) │ │ │ │ ┌───────────── day of the week (0 - 6) (Sunday to Saturday) │ │ │ │ │ * * * * *
How to use this tool
- Type or paste your raw cron expression consisting of 5 asterisks/numbers into the input box.
- The parser instantly processes the math required to translate the syntax.
- A large blue human-readable translation (e.g., 'At 22:00, Monday through Friday') will immediately appear.
- Click the quick-load example buttons below to learn how wildcards and divisions operate.
Example Usage
0 2 * * 1-5
At 02:00, Monday through Friday
*/15 * 1,15 * *
Every 15 minutes, on day 1 and 15 of the month
When to use this tool
- Validating that a database backup scheduled inside a production Ubuntu crontab is running at 3 AM standard time and not 3 PM.
- Verifying the precise syntax required to trigger a GitHub Action workflow daily.
- Learning the distinction between commas (lists), hyphens (ranges), and slashes (step values) in cron math.
Frequently Asked Questions
What are the 5 parts of a standard cron string?
Reading from left to right, the five fields strictly represent: Minute (0-59), Hour (0-23 in military time), Day of the Month (1-31), Month of the Year (1-12), and Day of the Week (0-6, where 0 is Sunday).
What does the asterisk (*) symbol mean?
The asterisk stands for 'first-to-last', representing every possible matching numeric value for that specific field. For instance, an asterisk in the 4th field means the job runs during every single month of the year.
How do I schedule something to run 'every X minutes'?
You utilize the forward slash division operator (/). To run a script every 15 minutes, you write `*/15` in the very first minute specific field. This translates mathematically to 'run at minute 0, minute 15, minute 30, and minute 45'.
Why does my cron string throw an 'Invalid syntax' error?
A standard POSIX cron string strictly dictates exactly 5 fields, separated by a single space character. If you provide fewer than five fields, or introduce unexpected alphabetical characters without proper macros, the parser cannot structurally map your schedule.
Does this parser support advanced 6-part string macros?
While basic Linux crontab structures use 5 parts, highly advanced schedulers (like AWS EventBridge or Quartz) inject a 6th parameter exclusively for the 'Year' constraint. This parser handles standard 5-part representations strictly.