LoupeKit

LoupeKit is a browser extension that floats a multi-surface inspection panel over any page you are viewing, letting you read the framework, extract the palette, measure the box model, and score how much of the page an AI generated — all without sending data off your machine. It is available for Chrome, Firefox, and Edge (plus any Chromium-based browser), requires no sign-up to use the free tier, and runs entirely in the browser for everything except a handful of server-side probes.

What It Is

LoupeKit is a developer and designer inspection tool packaged as a browser extension. It consolidates what would otherwise require four or more separate extensions — stack detection, UI inspection, SEO reading, accessibility auditing, and performance diagnostics — into a single panel with nine named surfaces and 70 individual tools and diagnostics. The panel floats over the page rather than docking beside it, so the page keeps its natural width while you inspect it.

Nine Surfaces, One Panel

The panel is organized into nine tabs, each reading the active tab:

• Stack — identifies technologies on the page, shows the selector, URL, or header that matched, and lists published CVEs against detected versions (Pro).
• Vibe — scores how much of the page reads as AI-generated using 66 heuristics across markup, CSS, runtime, copy, and accessibility categories; each heuristic quotes the value it fired on.
• UI — hover-to-inspect box model, typography, and colors; edit on the page and copy the change back.
• Tools — a grid of all 70 tools and diagnostics, each a reading of the open document.
• Developer — CSS overrides, outline toggles, image controls, user-agent switching, and 12 sections of page switches normally requiring DevTools.
• SEO — head metadata, heading outline, schema markup, social cards, crawler directives, and an AI-answers section.
• A11y — contrast ratios, accessibility tree, focus order, vision simulations, and WCAG conformance (Pro).
• Domain — WHOIS identity, DNS records, and TLS certificate details.
• Server (Pro) — server-side probes for redirects, consent signals, language negotiation, delivery headers, and link previews.

Privacy and Permission Architecture

LoupeKit ships with four permissions in its manifest — activeTab, storage, scripting, and contextMenus — and zero host permissions. The homepage states that a build test fails if a host permission appears. Optional permissions (declarativeNetRequestWithHostAccess, privacy, cookies) are requested only when specific features are turned on and are returned when those features are turned off. The extension collects no analytics, no trackers, no session replay, and no fingerprinting. For the Vibe audit — the only feature that leaves the machine — the payload is limited to a hostname, integer counts, class-name strings, and truncated heading text; no body text, input values, or full URLs are transmitted.

Seventy Tools and Diagnostics

The Tools tab exposes 34 tools (Classes, Wording, Viewport, Grid, Ruler, Fonts, Mockup, JSON, Tables, QR code, Print, Pseudoloc, Reader, Page theme, Copy inspect, Link builder, Site styles, Layers, Selector, Units, Cookies, Page source, Open URLs, CSS to Tailwind, WordPress, Picture-in-picture, Patterns, Capture, Encoders, and more) and 36 diagnostics (Cascade, Z-index, Compare, Shifts, Overflow, Reflow, Font loading, Forms, Environments, Page weight, Unused, Images, Focus path, Keyboard walk, Scrolling, Interactions, Errors, Console, Mutations, Tokens, Animation, Media, Outline, Head order, Iframes, Top layer, Storage, Hints, Service worker, Font faces, Tailwind theme, Preferences, and more). Pro-only tools include Recorder, Markdown, Client report, Component, Scraper, Load timing, Requests, Third parties, and Source maps. A command palette (⌘K / Ctrl+K) searches all 222 destinations — tools, sections, and settings — using substring matching only.

Browser Support and Deployment

LoupeKit ships two builds: one for Chromium-based browsers (Chrome, Edge, Brave, Opera, Arc, Vivaldi, Chromium, Opera GX) distributed via the Chrome Web Store and Microsoft Edge Add-ons, and a separate build for Firefox from version 140 and above distributed via Firefox Add-ons. The Firefox floor is 140 because that version introduced a built-in data-consent screen the extension relies on. Safari is not shipped, as it would require a third build and a native app wrapper. The extension does not run on mobile browsers because there is no toolbar to click and no panel to drag on a phone.

Current Status: Product Hunt Launch

The site displays a live Product Hunt launch banner at the time of crawl, indicating LoupeKit is in active public launch. The blog section lists articles dated August 2026, and the pricing page notes a lifetime plan at a launch price that will rise after launch. The changelog is linked from the panel's "What's new" screen and the website, with the site stating the release rate is "visible rather than promised."