Cron Expression Builder

Build a cron schedule with controls and read back when it will actually run.

IntermediateAutomationDev tool8–16hAI-buildable 4/5no setup

Nobody remembers cron syntax. This builds the expression from friendly controls and, more importantly, prints the next ten times it will fire in plain language. The parser-and-explainer is the real project; the form is the easy half.

Logic

Useful

Hosting · Free forever

Deploys free on GitHub Actions, Cloudflare Workers Cron or your own machine.

GitHub Actions runs scheduled jobs free on public repositories, so this can tick along without a server.

Runs on a schedule for free, or on your own machine.

Core features · 6

Controls for minute, hour, day-of-month, month and day-of-week
The cron expression updates live as controls change
Pasting an existing expression populates the controls
A plain-language description explains what the schedule means
The next ten run times are listed
Invalid expressions are rejected with a specific reason

The interesting part

Computing next-run times, especially where day-of-month and day-of-week interact
Round-tripping an arbitrary expression back into the control state
Generating readable prose from a parsed expression