Cron builder & explainer
A cron expression in English, with its next five runs.
Questions
What does this tool do?
The Cron builder & explainer reads a five-field cron expression and says it in English — At 09:30 on Monday to Friday — with the next five times it would run, in your zone. It goes the other way too: pick a frequency and a time and get the expression, or start from one of six presets for the usual jobs.
Which syntax does it read?
The standard five fields — minute, hour, day of month, month, day of week — with * for any, lists (1,15), ranges (1-5), steps (*/15, 1-30/5) and the names JAN–DEC and SUN–SAT. Sunday is 0 or 7. The aliases @hourly, @daily, @midnight, @weekly, @monthly, @yearly and @annually work too. Seconds and years, which some schedulers add, are not read.
How are day of month and day of week combined?
As cron does: when both are set, the job runs on either — 0 9 1 * 1 fires on the 1st and on every Monday. When one of them is *, the other decides.
Which zone are the next runs in?
In your browser's time zone, as the wall clock there. The server running the job may be in another zone — most are in UTC — so check where the job runs before you trust the hours.
What if the expression never fires?
Fewer runs, or none: 0 0 31 2 * never comes, and 0 0 29 2 * comes once every four years. The page lists what it finds within the next few years and says so when it finds nothing.
What can the builder set?
Every minute, hour, day, week or month, plus a time and a weekday or a day of the month where they apply. The expression updates as you change them; the six presets cover the jobs most people schedule.