About buildcron
buildcron is a free tool for reading and writing cron expressions. It explains any five-field cron schedule in plain English, turns plain-English schedules into cron, and shows when a job will next run — without an account, and without sending what you type anywhere.
Why it exists
Cron's syntax is compact to the point of being cryptic. Five fields of numbers and symbols decide when backups run, invoices go out and certificates renew, and a small mistake — a * where a 0 belonged, or a day of month and a day of week that quietly combine with OR — can mean a job that runs 60 times too often, or never runs at all. Most people write cron expressions a few times a year: just often enough to forget the rules in between.
buildcron is meant to be the quickest way to check. Paste an expression and you see what it does and when it will next run; describe a schedule and you get the expression — or a clear explanation of why cron can't do it, instead of an expression that's quietly wrong.
How it works
Everything happens in your browser. The validator, the plain-English translator and the run-time calculator are small pieces of code that run on your device, so results are instant and nothing you type is stored. The only preference the site saves is whether you chose the light or dark theme, which is kept in your own browser.
The explanations follow standard crontab behaviour — the rules implemented by Vixie cron and cronie on Linux, and used by Kubernetes CronJobs and GitHub Actions. The logic is covered by automated tests, including the awkward cases: the day of month / day of week OR rule, steps that don't divide evenly, and schedules that cron can't express at all.
Who builds it
buildcron is an independent project built and maintained by [Your name or company]. If you find an explanation that's wrong or unclear, or a schedule the tool should handle better, please say so on the contact page — corrections are the most useful feedback the site gets.
How it's funded
The site is free to use and supported by advertising from Google AdSense, shown in clearly labelled spaces away from the tool itself. Google Analytics, where you allow it, shows which pages and tool features are actually useful. The privacy policy explains how both use cookies and how to control them.
What's next
Optional job monitoring — an alert when a scheduled job doesn't run when it should — is planned. The cron tool itself will stay free and will keep working without an account.