Paste a cron line, pick a time zone, see what it means and when it runs next (daylight-saving aware).
curl 'https://cron.wickkit.cc/?e=*/15+9-17+*+*+1-5&tz=Europe/Berlin&n=5' curl 'https://cron.wickkit.cc/api?e=@weekly&tz=America/New_York' # JSON
Five fields (minute hour day-of-month month day-of-week), names like mon and jan, and the @daily-style macros.
When both day fields are set, a day matches if either matches, as in standard cron.
A time skipped by a daylight-saving jump doesn't run; a time that happens twice runs once.