Cron Builder

Anyone who has ever set up a cronjob knows that brief hesitation before hitting save: is the order right? Was 0 Sunday or Monday? Does this run only on the 10th, or every day at 10? Cron Builder takes that uncertainty away by assembling the expression field by field and telling you what it means as you go.

You start by choosing the format. The default is the classic five fields - minute, hour, day, month, weekday - as expected by Unix cron and most schedulers. Need second-level scheduling? Switch to the extended six-field format. And for Quartz-based systems there is the seven-field format including seconds and year. So the builder matches the scheduler you actually run.

For every field you see the allowed range - minutes 0 to 59, hours 0 to 23, weekdays 0 to 6 - and can combine single values, lists, ranges and step sizes. The assembled expression is explained live, turning the cryptic pattern into a readable sentence.

The centrepiece is the preview of the next run times. Instead of guessing whether your expression is right, you see concrete dates when the job would next fire. Especially for tricky day-and-weekday combinations, this is the fastest way to catch a thinking error before it hits production.

So you do not start from scratch for every standard case, the builder ships 24 ready-made templates sorted into categories. Alongside the classics like every 5 minutes or daily at midnight, there are typically German bureaucratic dates: the monthly advance VAT return on the 10th, the quarterly tax, the payroll tax filing or the social-insurance report at month-end. Plus business rhythms (Monday meeting, Friday report) and system classics (nightly backup, weekly cleanup, log rotation).

Cron Builder runs entirely in your browser. Nothing is sent to a server and nothing is stored. You simply copy the finished expression into your crontab, your CI job, your BullMQ scheduler or wherever it needs to go. No account, no signup, no data leaving your device.