PrivacyTests.org is an open source privacy audit of popular web browsers. The project subjects web browsers to automated leak tests and regularly publishes the browsers’ test results head-to-head on a website and on social media. The goal of PrivacyTests is to encourage all web browsers to mend their ways and comprehensively protect everyone’s privacy. By thoroughly exposing the leaks in web browsers, the website helps users choose a more private browser, and thereby puts pressure on browser makers to fix their privacy leaks. In his talk, Arthur will give some details about the project’s approach to testing and presenting test results, and show how browser privacy has evolved over the past four years.