🚀 Quick Takeaways What it does: A checker reads public signals such as HTTP headers, scripts, cookies and meta tags, then matches them against a fingerprint database. Two market leaders: Wappalyzer dominates quick browser checks, while BuiltWith owns historical archives and web-wide trend data. Real prices: Wappalyzer’s paid tiers run from $250/month (Pro) to $850+/month..