Internet advertising companies like Google and Yahoo! obtain private information about you by watching what websites you visit. We are researching how to design and build advertising systems that allow for personalized advertising while respecting your privacy. We have built an experimental prototype of Privad system (see here for an overview) to demonstrate feasibility of client-side interest-based non-tracking advertising model. In this model no user-related information is collected by the backend servers and ads are targeted based solely on the user profile information which is stored locally on the user computer and never leaves user computer. The only information that reaches backend servers are individual and unlinkable ad requests and view/click reports.

The experimental nature of our system means that we neither work with any commercial advertising companies nor generate any revenue by displaying ads. Instead, we create mock-up ads using product listings from, and As far as profiling and targeting goes, we are experimenting with two simple heuristics: search-based targeting and product-based targeting. First looks at user keyword searches and flags them as product-relates or not by looking up individual terms in a dictionary built from words that appear more than a 100 times in titles of ca. 80 million products randomly retrieved from, and Second identifies the specific product the user is browsing by checking if the currently displayed page is a shopping website and by applying a scraper customized for this particular shopping website. These heuristics are only used with a number of whitelisted websites (which includes major search engines and most popular online retailers).

Privad client uses identified product titles and product-related keywords to request ads from the backend infrastructure in an anonymous, privacy-preserving manner (described here). Backend servers use these ad requests to search for matching products on, and and build textual ads from the resulting products. The client then stores these mock-up Privad ads on the user computer and displays them in Google adboxes instead of Adsense ads.

Another experimental feature in Privad addon is differentially private data aggregation. What it means in practical terms is that Privad client locally collects ads-related statistical data and allows for numerical queries over these data with some amount of noise added to the query results. This mechanism makes it possible to obtain deep insight into ads performance, which goes beyond simple click-through and conversion-rates, without forfeiting user privacy.

If you are a Firefox user, by installing the addon below you can help us to show that advertising does not require tracking! The addon will use our system to serve you ads related to products you are shopping for. You won't notice any difference (apart from the difference in ads you receive), but we'll obtain valuable research results.

Privad Client

Firefox Addon