AWS Cron Validator

A valid AWS cron expression in 6 fields.

How it works

• Split the expression into the six AWS fields.
• Parsed '*' and '?' wildcards, ranges, steps, lists, month/day names, and the L/W/# specials.
• Listed the next occurrences strictly after the supplied reference instant in UTC.

• AWS evaluates cron in UTC and requires exactly one of day-of-month/day-of-week to be '?'.
• The tool never reads the system clock; supply a reference to see occurrences.

Methodology

1. Parse each of the six fields with AWS min/max ranges, month/day names and the L/W/# specials.
2. Require exactly one day-of-month/day-of-week field to be '?'.
3. Match candidate UTC instants from the supplied reference and list the next occurrences.

Usage

1. Enter a six-field AWS cron expression (minutes hours day-of-month month day-of-week year).
2. Optionally supply a reference ISO-8601 timestamp and the number of occurrences.
3. Read the parsed fields, the description and any errors.

Examples

These are examples, not current values: they use fixed inputs, while the interactive tool computes live results in your browser.

Every day at noon

{
  "expression": "0 12 * * ? *",
  "reference": "2026-01-01T00:00:00.000Z",
  "count": 3
}

Last weekday of the month

{
  "expression": "0 9 LW * ? *",
  "reference": "2026-01-01T00:00:00.000Z",
  "count": 2
}

Limitations

AWS cron specials

`?` ignores a day field, `L` means the last day of the month (or the last given weekday), `W` means the nearest weekday, and `#` selects the nth weekday (for example `3#2` is the second Tuesday).