DEV3 Free Broken Link Checker — Source Code (Next.js + MongoDB)

Source code of the DEV3 Broken Link Checker, a Next.js crawler endpoint and UI that follow a site with an SSRF-safe fetcher, check up to 300 links and stream progress with a CSV report.

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

What is in the download

• Route handlers and pages for the Next.js App Router
• The service layer, Mongoose models and the UI components, in a dev3-tools/ folder that cannot clash with your own files
• README.md (install, environment, customise), .env.example and an MIT LICENSE

What the code does

• Same-site crawl with page, link and time budgets
• SSRF-safe fetch with redirect handling
• HTML link extraction and resolution helpers
• CSV export of broken links and where they were found

Tech stack

Next.js 15 (App Router), React 19, TypeScript, Mongoose on MongoDB, Tailwind CSS 4.

Install and customise

The How to install and How to use tabs list the steps. In short: copy the module into a Next.js app, install the listed packages, add the MongoDB connection string and run it.

Good to know

• This is server code: you need a MongoDB database and your own hosting.
• Pages that need JavaScript to render their links are not seen, because the crawler reads raw HTML.