Build a cron expression from dropdowns

Pick a value for each of seven fields, second, minute, hour, day of month, month, day of week and year, and the expression assembles at the top with a copy button. Each dropdown lists the forms people actually need: a single value, every N (*/5), a range (9-17), a list (1,15) and, for day of month, L for the last day. Fourteen presets cover the usual schedules, from every minute to weekdays at 9 AM to the first of the month, and loading one fills in the fields so it can be adjusted.

The seven-field layout with seconds and an optional year is the Quartz format used by Spring, Quartz Scheduler and several cloud schedulers. Classic Unix crontab uses five fields and has neither seconds nor a year, so for a crontab entry drop the first and last fields. Quartz itself also insists that one of day of month and day of week be a question mark rather than an asterisk, so replace one before pasting into a trigger. The description line explains a preset in plain words; a custom combination is labelled as such rather than guessed at.

Two things the generator cannot know: the timezone the scheduler runs in, which is usually the server's and not yours, and whether consecutive runs overlap. Check both before deploying. A second tab holds the regex tester, for when the same session involves parsing the job's output.