DEV3 Free Cron Expression Builder — Source Code (React + Tailwind)

Source code of the DEV3 Cron Expression Builder, a cron parser and visual builder that explains an expression in words, validates each field and computes upcoming run times in any time zone.

Free download: sign in to any DEV3 account and click Download ZIP. Try it live: https://dev3.tech/tools/cron-expression-builder shows the finished tool running.

What is in the download

• A standalone Vite + React + TypeScript + Tailwind CSS project: src/tool holds the tool, shared pieces sit beside it
• package.json with exact versions plus a lockfile, so npm ci works
• README.md (run, build, embed in Next.js or plain React) and an MIT LICENSE

What the code does

• Five- and six-field cron parsing with field-level errors
• Plain-language description of the schedule
• Next ten runs calculated for a chosen time zone
• Crontab line output

Tech stack

React 19, TypeScript, Vite, Tailwind CSS 4.

Install and customise

The How to install and How to use tabs list the steps. In short: unzip, npm ci, npm run dev, then copy the tool folder into your own app if you want to embed it.

Good to know

• A browser-only tool: there is no backend or database in the code.