# nebx Cron Expression Editor

> Free cron expression editor and generator: plain-English descriptions, next run times in any time zone, a visual builder and support for crontab, Quartz, AWS and GitHub Actions schedules. Runs in your browser.

Part of nebx (https://nebx.ai/). About nebx and its other tools: https://nebx.ai/llms.txt

- Plain-English description of any cron expression
- Next run times in your time zone or any other, with daylight-saving notes
- Visual builder for every field, plus one-click presets
- Dialects: Linux crontab, crontab with seconds, Quartz, AWS EventBridge and GitHub Actions
- Converts expressions between dialects when they can be expressed
- Special characters: ranges, lists, steps, @daily-style macros, L, W and #
- Calendar of upcoming runs for the next six weeks
- Ready-to-paste snippets for crontab, Kubernetes, GitHub Actions, AWS, node-cron and Quartz
- Library of common schedules and a field reference

Q: What do the five fields of a cron expression mean?
A: In order: minute (0–59), hour (0–23), day of the month (1–31), month (1–12 or JAN–DEC) and day of the week (0–7 or SUN–SAT, where 0 and 7 are both Sunday). An asterisk means every value; for example 30 9 * * 1-5 runs at 09:30 Monday to Friday.

Q: Why does my job run on more days than I expected?
A: In standard cron, if both the day-of-month and day-of-week fields are restricted, the job runs when either one matches, not both. 0 0 1 * MON runs on the 1st of every month and also every Monday. The description here spells this out.

Q: Which time zone do cron jobs use?
A: It depends on the system. Linux crontab uses the server's local time zone, GitHub Actions schedules always use UTC, and Kubernetes CronJobs use the controller's time zone unless you set spec.timeZone. Pick the time zone here to see the next runs as that system will.

Q: What is the difference between crontab, Quartz and AWS cron?
A: Quartz adds a seconds field in front and an optional year at the end; AWS EventBridge adds a year at the end. Both number weekdays 1–7 starting with Sunday, need ? in either the day-of-month or day-of-week field, and support L, W and #. Use the dialect switch to check an expression for each.

Q: Is anything uploaded?
A: No. Parsing, descriptions and next run times are calculated in your browser. Nothing is sent to a server, and a share link keeps the expression in the part of the URL after #.