See what advertising/tracking scripts observe about you. Passive, local-only logging of fingerprinting attempts, third-party trackers, and cookie syncing — with a built-in report dashboard.
AdTech Mirror passively watches what advertising and analytics scripts try to learn about you as you browse, and turns it into a plain-language report — entirely on your own device. Nothing is ever sent anywhere.
Third-party trackers — flags requests to ~50 known ad networks, ad exchanges, SSPs/DSPs, data management platforms, identity-resolution services, and data brokers (Google/DoubleClick, Meta Pixel, TikTok Pixel, Amazon Advertising, The Trade Desk, PubMatic, Magnite, Criteo, Adobe Audience Manager, Oracle BlueKai, LiveRamp, ID5, FingerprintJS, and many more), categorized by type.
Browser fingerprinting — detects when scripts try to fingerprint your device via Canvas rendering, WebGL/GPU parameters, AudioContext processing, font enumeration, the Battery API, and sensitive navigator properties (hardware concurrency, device memory, languages, etc.).
ID syncing — flags requests where tracking IDs appear to be shared between ad companies behind the scenes ("cookie syncing"), a key mechanism for linking your identity across services.
Cross-site identity linking — shows which trackers followed you across multiple different sites, indicating they could be building a unified profile of your browsing.
Outbound link leakage — notes when clicking a link sends your referrer/page info to an ad/tracking domain.
A small floating button (🛰️) opens a report showing:
All data is stored locally in your browser's IndexedDB (90-day auto-pruning). The script makes no network requests of its own and sends no data anywhere — it only observes traffic and API calls your browser is already making as you browse normally.
The tracker domain list is not exhaustive and may need updates as ad-tech vendors change. This is a passive observation tool — it does not block anything (pair it with uBlock Origin if you also want blocking). Works best if left running for at least a week or two of normal browsing before checking the report and this script is NOT perfect.
