How Mozilla moved fast to block Facebook and other privacy invaders from your web browser

When Facebook users learned last March that the social media giant had given their sensitive information to political-data firm Cambridge Analytica, Mozilla (parent company of the security-focused browser Firefox) reacted fast: Within eight hours, the product team had built a browser extension called the Facebook Container. The plug-in, now the most popular browser extension Mozilla has ever built (1.5 million downloads and 500,000 monthly active users), prevents Facebook from trailing its users around the internet. Firefox Monitor, a service Mozilla launched in September, uses your email address to determine whether your personal info has been compromised in a breach. By summer 2019, the Firefox browser will also block, by default, all cross-site third-party trackers, strengthening privacy without your having to do a thing (unlike Firefox’s biggest competitor, Google Chrome). “We want to make it simple for people to create walls around data that’s important to them,” says Denelle Dixon, Mozilla’s COO.