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Cron expression generator

4 dialects · L, W and # where supported · round-trips an existing expression

Pick values for each field and the expression is written as you go, in the dialect you choose — seconds, ? and weekday numbering handled for you. Every result is re-read by the parser, so the sentence and the next runs are what the scheduler will actually do.

Dialect Time zone for the runs Day and month names (MON, JAN)

Edit an existing expression

Fields

Next 5 runs

How to build a cron expression

Choose the dialect the scheduler speaks: Linux crontab (Unix), Quartz, AWS EventBridge or Spring @Scheduled. Quartz and Spring get a seconds field; AWS gets the year field and the cron( … ) wrapper.
For each field pick how to choose values — every, every N, specific values, a range — and click the values. The field's text appears next to its name as you go.
Read the sentence under the expression. It comes from parsing the result, not from your clicks, so it is the schedule the dialect will really run.
Check the next five runs in your time zone, fix anything marked in red, then press Copy expression.
To change an expression you already have, paste it into Edit an existing expression. The builder loads each field into its controls and keeps anything it has no control for as custom text.

What changes between the four dialects

	Unix cron	Quartz	AWS EventBridge	Spring
Fields	min hour dom mon dow	sec min hour dom mon dow [year]	cron(min hour dom mon dow year)	sec min hour dom mon dow
Monday to Friday	1-5	MON-FRI or 2-6	MON-FRI or 2-6	1-5 or MON-FRI
Both day fields set	runs when either matches	not allowed — one must be `?`	not allowed — one must be `?`	runs only when both match
L, W, #	no	yes	yes (LW and L-n not documented)	yes
Every 15 minutes	/15 * * *	0 0/15 * * * ?	cron(0/15 * * * ? *)	0 /15 * * *

The weekday numbers are the trap: Quartz and AWS count 1 = Sunday to 7 = Saturday, so a Linux 1-5 copied across means Sunday to Thursday. With names ticked (the default for Quartz and AWS) the builder writes MON-FRI and the question does not arise. For Linux crontabs, numbers are safer: Debian's cron does not accept ranges or lists of names, cronie does. The cheat sheet has the full comparison.

The special characters it can add

In Quartz, AWS and Spring the day-of-month field offers L (last day, or L-3 for three days before it), LW (last weekday) and 15W (the weekday nearest the 15th — Quartz does not cross into another month, so 1W on a Saturday is Monday the 3rd). The day-of-week field offers 2#1-style "first Monday" and 6L-style "last Friday"; the builder writes these with numbers in the dialect's own numbering. Unix cron has none of them — switch to Unix with one selected and the builder says so; the cheat sheet shows the shell tests that stand in for them.

FAQ

Why does Quartz output have a question mark?

Quartz and AWS EventBridge do not support setting both the day of month and the day of week. The field you are not using must be ? ("no specific value"), so the builder puts it there: ? in day-of-week when you pick dates, ? in day-of-month when you pick weekdays.

I picked a day of the month and a weekday. What will run?

It depends on the dialect. Linux cron runs on either (the 1st or any Monday), Spring only on days that are both, and Quartz and AWS refuse the combination. The sentence under the expression spells out which rule applied.

Can I paste an expression and change one field?

Yes. Paste it into Edit an existing expression; the dialect is detected from its shape. Lists, ranges and steps load into the matching controls. A field the controls cannot hold — for example 1,15,L — is kept as custom text, and the builder confirms the rebuilt expression gives the same runs as yours.

How do I write "every 90 minutes" or "the last Friday" for Linux?

Neither fits one Linux crontab line. Every 90 minutes takes two lines (0 0-21/3 * * * and 30 1-22/3 * * *); the last Friday needs a shell test in the command. Text to cron writes both for you.