Cron Expression Parser & Generator

Cron Expression Parser & Generator online

Cron expressions schedule recurring jobs on servers, in CI pipelines and inside many application frameworks. They are compact but cryptic: a handful of numbers and symbols can decide whether a backup runs every night or only on the last Friday of the month. This tool turns any cron string into a plain-English sentence and lists the next five times it will fire, and it can also build an expression for you through a visual selector. It detects the standard five-field format as well as the six-field and seven-field Quartz formats that add seconds and an optional year.

How to use this tool

1. Open Cron Expression Parser & Generator in a modern browser.
2. Paste a cron expression or use the visual builder to generate one.
3. Review the field breakdown, the plain-English meaning and the next five run times.
4. Copy the result when you need to reuse it elsewhere.

Supported formats

A standard cron expression has five fields separated by spaces: minute, hour, day of month, month and day of week. Quartz-style schedulers add a leading seconds field, and some add a trailing year field, giving six or seven fields. This parser counts the fields automatically, so you can paste an expression from crontab, Spring, Kubernetes CronJob or Quartz without reformatting it first.

Field reference

Special characters

• * matches every value in the field.
• */n is a step, for example */15 in the minute field means every 15 minutes.
• a-b is an inclusive range, such as 9-17 for business hours.
• a,b,c is a list of specific values.
• L means the last day of the month, or the last given weekday when used in the weekday field.
• W finds the nearest weekday to a date, useful for payroll and billing tasks.
• # selects the nth weekday of the month, for example 2#3 is the third Tuesday.
• ? means “no specific value” and is common in Quartz expressions.

Day-of-month versus weekday

When both the day-of-month and the day-of-week fields are restricted, cron treats them as an OR. The expression 0 9 1 * 1 therefore runs at 09:00 on the first day of the month or on every Monday. Understanding this rule prevents a common class of scheduling surprises where a job runs far more often than intended.

Common presets

• * * * * * — every minute.
• 0 * * * * — every hour on the hour.
• 0 0 * * * — every day at midnight.
• 0 9 * * 1 — every Monday at 09:00.
• 0 0 1 * * — the first day of every month.
• */15 9-17 * * 1-5 — every 15 minutes during business hours on weekdays.

Privacy and browser processing

Everything runs locally in your browser. The expression you paste is never uploaded, and the next run times are computed against your own device clock and timezone.

Frequently asked questions

What does L mean in a cron expression?

In the day-of-month field, L means the last day of the month. In the weekday field it means the last occurrence of that weekday in the month, so 5L is the last Friday.

What does W mean in a cron expression?

W finds the nearest weekday to a given day. 15W means the weekday closest to the 15th, which is useful when a task must run on a business day.

What does # mean in a cron expression?

# selects the nth weekday of the month. 2#3 means the third Tuesday of the month.

How are the next run times calculated?

The tool matches the expression against your browser’s local time, minute by minute, for up to 366 days ahead.

Does this tool upload my cron expression?

No. Parsing and generation happen entirely in your browser.

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