How It Works

This tool generates CRON expressions from a simple point-and-click interface — entirely inside your browser. No data is sent to a server.

What is a CRON Expression?

A CRON expression is a string of five fields separated by spaces that defines a recurring schedule for a job scheduler (cron daemon on Unix, GitHub Actions, AWS EventBridge, etc.). Each field controls one dimension of time:

| Position | Field | Allowed Values | Special Characters | |----------|-------|----------------|--------------------| | 1 | Minute | 0–59 | * , - / | | 2 | Hour | 0–23 | * , - / | | 3 | Day of month | 1–31 | * , - / ? | | 4 | Month | 1–12 | * , - / | | 5 | Day of week | 0–6 (Sun–Sat) | * , - / ? |

An asterisk (*) in a field means “every valid value for that field.” For example, 0 9 * * 1 means “at 09:00 every Monday.”

Implementation Details

The generator is written in plain JavaScript. When you click Generate, the selected frequency and time values are read from the form controls and assembled into a five-field CRON string using simple string concatenation. A human-readable description and a field-by-field reference table are then rendered directly in the page without any page reload.

All scheduling logic runs in the browser — no network requests, no backend, no libraries. Time values (hours) follow UTC unless your scheduler interprets them otherwise.

Common Examples

| Expression | Meaning | |------------|---------| | * * * * * | Every minute | | 0 * * * * | Every hour (at :00) | | 0 9 * * * | Every day at 09:00 UTC | | 0 9 * * 1 | Every Monday at 09:00 UTC | | 0 9 1 * * | First day of every month at 09:00 UTC |

Privacy

Everything runs locally in your browser. No schedule data is transmitted anywhere.