How I Built a 9-Tool SEO Audit Suite Without a Single Browser Automation

Every tool runs on Node.js without Playwright or Puppeteer. Here's how: The Tools SEO Audit — CheerioCrawler checks 50+ factors Broken Links — CheerioCrawler follows internal links PageSpeed — Google's free PSI API (no key) SSL Checker — Node.js https module reads certs directly Headers Checker — HTTP HEAD request + 10-header checklist Tech Detector — Regex on HTML source + response headers Sitemap Parser — cheerio with xmlMode Robots.txt — fetch + text parsing Keyword Density — word frequency + bigram analysis Why No Browser? For SEO audits, you're analyzing HTML structure — not rendering JavaScript. Cheerio (HTML parser) uses 50MB RAM vs 500MB for Playwright. Runs 10x faster. The only tool that could benefit from a browser is PageSpeed — but Google already does the rendering via their API. The Robots.txt Analyzer Is My Favorite It detects which AI bots a site blocks: { "blockedBots" : { "GPTBot" : true , "ClaudeBot" : false , "CCBot" : true , "Googlebot" : false }, "aiBotsBlocked" :