Cronly

Explain, build and browse cron schedules in plain English — a full cron toolkit, on-device, no login.

Cron's five fields are easy to write and hard to read back, and the mistake is rarely a syntax error — a wrong expression is almost always valid, so it schedules something, just not what you meant, and nothing tells you until the run that did not happen.

The classic trap is that day-of-month and day-of-week combine with OR rather than AND, so an expression naming both fires on either. Reading the schedule back in plain English and seeing the next few run times is the fastest way to catch that, because the English version makes the OR obvious where the syntax hides it.