LoupeKit

LoupeKit is a browser extension for reading somebody else's page the way you would read your own. It floats a panel over the page rather than docking to devtools, which keeps the page at full width while you inspect it, and organises 70 tools across nine tabs: Stack (technologies, known vulnerabilities, HTTP headers), UI (element inspection, design-property extraction, live CSS editing), Tools (grid overlays, rulers, colour extraction, font analysis), Developer (CSS debugging, outlines, image inspection, form validation), SEO (metadata, structured data, crawler readiness), A11y (contrast, focus path), Domain (registration, DNS, certificates) and Server.

The tab that gives it its hook is Vibe, an audit that scores how much of a page looks machine-written using 66 heuristics across five weighted categories — a practical signal for agencies and buyers doing diligence on a site they did not build. A ⌘K command palette searches over 200 functions so none of this depends on remembering which tab holds what.

Privacy is treated as an architectural constraint rather than a policy page. The extension requests only four permissions — activeTab, storage, scripting and contextMenus — with no host permissions at all, and the vendor states a test fails if one appears. Analysis runs locally; the audit, the one metered feature, transmits only a hostname, integer counts, class-name strings and truncated, redacted title and heading text.

It runs on nine browsers from two builds: Chrome, Brave, Opera, Opera GX, Arc, Vivaldi and Chromium, plus Firefox 140+ and a native Edge build. Safari is not supported. The free tier gives unlimited page reading, basic inspection and three vibe audits; €6.99/month unlocks unlimited audits, client reports, baselines and evidence packs, and a €74.99 lifetime licence (rising to €119.99) covers the same features one-time.