Why it exists

Cookie banners ask you to "manage preferences" for a tracking apparatus no human can see, let alone evaluate. Who is actually over your shoulder while you shop, learn or read the news? Blacklight — built by The Markup and used in their Pulitzer-finalist investigations — answers with evidence: it loads the site like a visitor would and reports the specific tracking technologies found, from Facebook and TikTok pixels to scripts that record your keystrokes before you hit submit. Thousands of scans feed their reporting on who tracks hospital patients, students and voters.

Main features

• Seven real-time tests — ad trackers, third-party cookies, cookie-blocker evasion (fingerprinting), session-recording scripts, keystroke capturing, Facebook pixel, TikTok pixel.
• Scan options — choose location (Ohio/California/Europe) and device type (mobile/desktop), with fresh or cached results.
• Plain-language verdicts — each test ends with a clear yes/no and the names of the companies receiving data.
• Replicable — the collector is open source, so auditors and journalists can run their own inspections.

Who it's for

• Journalists, researchers and lawyers auditing sites' claims about privacy.
• Developers and product owners who genuinely don't know what their third-party scripts do.
• Anyone about to enter personal data into a site and wanting 30 seconds of evidence first.

How it compares

• PrivacySpy (in this library) — grades the written policy; Blacklight tests the actual behavior.
• Privacy Badger / uBlock — block trackers for yourself; Blacklight documents them for everyone.
• BuiltWith / Wappalyzer — identify the tech stack; Blacklight focuses specifically on the surveillance parts.
• DuckDuckGo Tracker Radar — dataset-level tracker intelligence; Blacklight gives per-site live results.

Notes

• Results reflect one scan from one location — heavy sites can behave differently per visit; use the "force request, no caching" option for fresh evidence.
• A scan takes roughly 30–60 seconds; the site collects only the URL you scan.
• The methodology and code (blacklight-collector, blacklight-query) are public, which is what makes its findings citable.

Useful links

• Tool: https://themarkup.org/blacklight
• Source: https://github.com/the-markup/blacklight-collector
• The Markup: https://themarkup.org/ (also in this library)