A Chrome extension that shows you exactly how a page is tracking, attributing and redirecting — with zero data leaving your browser.

Installation · Features · How it works · Demo · Privacy · Roadmap

Marketing attribution breaks silently. A fbclid gets stripped by a redirect, a _fbc cookie never gets set, a pixel fires three times, a UTM disappears after a consent banner reload — and nobody notices until the reports look wrong.

TrackLens puts a lens on the current tab and shows you the whole attribution picture in one popup: URL parameters, cookies, storage, the redirect chain, and every tracking request from the major ad platforms. It then flags the common failure patterns and gives you a health score.

No backend. No account. No API key. No telemetry. Everything runs inside Chrome.

✨ At a glance 🔎 Parameters Every query param, with ad-tech IDs recognised 🍪 Cookies All cookies for the current URL 🗄️ Storage LocalStorage + SessionStorage snapshot 🔀 Navigation Top-level redirect / navigation chain 📡 Requests Pixel & analytics calls, classified by vendor ⚠️ Issues Automatic attribution problem detection 💯 Score A simple tracking health score 📦 Export One-click local JSON debug report

TrackLens parses the active tab URL and highlights the identifiers that matter for attribution:

The background service worker watches outgoing requests and classifies hits to the major platforms:

TrackLens cross-references params, cookies, navigation history and requests to surface the problems that actually break attribution:

• 🔴 fbclid present in the URL but the _fbc cookie was never set
• 🔴 Meta pixel is firing but the _fbp cookie is missing
• 🟠 A click ID or UTM was present earlier in the redirect chain but has been lost on the final page
• 🟠 The same tracking request appears to be firing multiple times (duplicate pixels)

Each issue costs 15 points off a 100-point Tracking Health score, so you can eyeball a page's status in a second.

Anything that looks like a secret — keys matching token, secret, password, authorization, api_key, session — is masked in both the UI and the export (abc***xyz). You can share a debug report without leaking credentials.

One click produces a timestamped tracklens-report-*.json containing the page snapshot, params, cookies, navigation chain, tracking requests, detected issues and score. Perfect for attaching to a bug ticket or sending to an agency.

flowchart LR
    classDef page fill:#151d33,stroke:#365cff,color:#e8ecf7,stroke-width:2px
    classDef ext fill:#111827,stroke:#7c5cff,color:#e8ecf7,stroke-width:2px
    classDef store fill:#14251d,stroke:#22c55e,color:#e8ecf7,stroke-width:2px
    classDef ui fill:#1e1b4b,stroke:#22d3ee,color:#e8ecf7,stroke-width:2px

    subgraph Browser["🌐 Chrome tab"]
        P[Web page<br/>URL · cookies · storage]:::page
        CS[content.js<br/>storage snapshot]:::ext
    end

    subgraph SW["⚙️ Service worker"]
        BG[background.js]:::ext
        NAV[webNavigation<br/>redirect chain]:::ext
        REQ[webRequest<br/>tracker requests]:::ext
    end

    ST[(chrome.storage.session<br/>per-tab, wiped on close)]:::store

    subgraph Popup["🔍 Popup · React"]
        UI[Overview · Params · Cookies<br/>Storage · Navigation · Requests · Issues]:::ui
        AN[Issue engine + health score]:::ui
        EX[JSON export]:::ui
    end

    P --> CS
    P -. navigations .-> NAV
    P -. pixel calls .-> REQ
    NAV --> BG --> ST
    REQ --> BG
    CS -- message --> UI
    ST --> UI
    P -- chrome.cookies --> UI
    UI --> AN --> EX

1. Open chrome://extensions
2. Toggle Developer mode in the top-right corner
3. Click Load unpacked
4. Select the dist/ folder from this repository
5. Pin TrackLens to the toolbar and open any web page 🎉

# install dependencies
npm install

# production build → dist/
npm run build

# or run Vite in dev mode for the popup UI
npm run dev

Then load dist/ as an unpacked extension as described above.

The repo ships with a tiny demo page that sets cookies, writes to storage and fires fake Meta / Google pixel calls so you can see every tab light up.

# from the repository root
python3 -m http.server 8080

Then open:

http://localhost:8080/dist/demo/?fbclid=demo123&utm_source=facebook&utm_campaign=test&ad_id=42

Click the TrackLens icon and you should see recognised parameters, a _fbp cookie, a masked api_token in LocalStorage, and at least one detected issue (the fbclid is there but no _fbc cookie is set).

tracklens/
├── public/
│   ├── manifest.json      # MV3 manifest
│   ├── background.js      # service worker: navigation + request capture
│   ├── content.js         # storage snapshot on demand
│   └── demo/index.html    # local test page
├── src/
│   ├── main.tsx           # popup UI, issue engine, export
│   └── styles.css         # dark theme
├── dist/                  # ready-to-load build
├── assets/                # README artwork
└── index.html             # popup entry

• Manifest V3 boundaries. MV3 does not expose DevTools-grade request/response introspection. TrackLens focuses on request URLs, browser state, navigation and attribution signals that can be captured locally without a backend.
• Heuristic issues. The issue detector is intentionally simple and opinionated. Treat it as a fast smoke test, not a compliance audit.
• Popup-time snapshot. Cookies and storage are read when the popup opens. Hit Refresh after the page changes.

• Decode common pixel payloads (Meta ev, GA4 en) into readable events
• Consent-mode awareness (detect CMP state vs. pixel firing)
• Per-vendor request timelines
• Configurable custom parameter & endpoint lists
• Side-panel mode for long debugging sessions
• Optional light theme

Issues and pull requests are welcome. If you have a real-world attribution bug that TrackLens missed, open an issue with an exported JSON report (secrets are masked automatically) and describe what you expected to see.

Released under the MIT License.

_{Built for marketers, analysts and developers who are tired of guessing why the numbers don't match.}