LookUp — Page Health Scanner

Score any page 0-100, see what's broken with evidence, and get plain-English fixes. 100% on-device. Free.

LookUp checks the health of any web page and shows you exactly how to fix what's wrong — without sending a single byte off your device. One click gives the page a 0–100 score across five areas — Performance, Accessibility, Errors, Network, and Best Practices — and lists every issue with the real evidence behind it: the stack frame, the failed request, the exact element's HTML captured from the live page. But LookUp doesn't stop at "what's wrong." It shows you HOW to fix it: • PINPOINT THE CODE — On your localhost dev server, findings open an editor-style code frame at the exact file and line, resolving minified bundles through source maps back to your original TypeScript. • PLAIN-ENGLISH FIXES — Every finding has a step-by-step fix and a "why it matters," with framework-specific advice for React, Vue, Angular. • HAND IT TO YOUR AI EDITOR — One click copies a complete, ready-to-paste prompt (URL, file:line, evidence, element, fix) for Cursor, Claude Code, or any AI editor. DAILY DEVELOPER TOOLS, TOO: • CONSOLE COMMAND CENTER — a live stream of console and network problems with JS-heap and main-thread meters, updating as you interact. • STORAGE & STATE MANAGER — view, edit, search and bulk-manage localStorage & sessionStorage, with a JSON viewer and a JWT inspector. Save whole state snapshots and restore them in one click (logged-in ↔ logged-out). • DEV WATCH MODE — auto-rescans your dev server on every reload. SHARE & TRACK: • SHARE SCORE CARD — a signed, tamper-evident score image anyone can verify by re-scanning. • HISTORY — score trends and a new-vs-fixed diff between scans. • VIBE-CODE AUDITOR — a score for how "finished" AI-generated pages really are. • BLOAT X-RAY — third-party scripts ranked by cost. PRIVATE BY DESIGN: • 100% on-device. No account, no telemetry, no network calls — verifiable in the Network panel. • Optional AI explanations run locally via Chrome's built-in Gemini Nano. With AI off, everything still works with built-in wording. • Deterministic: the same page state always gives the same result. Free. Open a page, click LookUp, and see what your users are really getting. Keyboard shortcut: Alt+Shift+L