How to Build a Broken Link Checker in JavaScript (Free API)

Dead links destroy user experience and tank your SEO. Google penalizes pages with broken outbound links, and users bounce when they hit 404s. Most link-checking tools are either expensive SaaS products or slow crawlers that hammer servers. In this tutorial, we'll build a fast broken link checker using JavaScript and a free web scraping API — no Puppeteer, no headless browsers, no dependencies. What We're Building A CLI tool that: Scrapes all links from any webpage Tests each link for HTTP errors (404, 500, timeouts) Takes screenshots of broken destinations (proof for reports) Outputs a clean report with actionable results Prerequisites Node.js 18+ A free API key from Frostbyte (200 free credits, no card required) Step 1: Extract All Links from a Page First, let's use the web scraper API to pull every link from a target page: const API_KEY = process . env . FROSTBYTE_KEY || ' your-api-key ' ; const BASE = ' https://api.frostbyte.dev ' ; async function extractLinks ( url ) { const res =