Free DecryptAds Tool Shows Which Companies Are Tracking You Through Websites and Apps

Working out who is responsible for the ads on a website, or who collects data from the mobile apps we use, has been difficult. According to Krebs on Security, that information is semi-public but hard to parse, and much of it has stayed in the hands of large advertising platforms. A new free service, DecryptAds (decryptads.com), aims to change that by scraping and correlating this adtech data so users can quickly learn about the entities tracking them.

The service says it constantly collects files that websites and apps publish to disclose which companies may run ads or collect user data. These include ads.txt, app-ads.txt for mobile and smart TV apps, and buyers.json and sellers.json, which list who buys, sells or resells ad inventory. Zach Edwards, chief research officer for DecryptAds and a threat researcher at Infoblox, said the data is only useful when cross-referenced to build a fuller picture of each site or app.

Edwards said the tool takes a security approach to adtech. Intended uses include tracing the source of malicious ads that try to push malware onto users, identifying ad networks based in adversarial nations, and spotting the fast growing wave of AI-generated low quality websites and apps. He noted these risks are near impossible to detect by viewing a single file alone.