What Firefox Actually Does Differently for Privacy: A Technical Comparison

Technical privacy differences between Firefox and Chrome that matter: 1. Fission + Total Cookie Protection: Cross-origin iframes isolated in separate processes AND each top-level site gets its own cookie jar. Third-party cookies can’t leak cross-site. This is stronger than Chrome’s Privacy Sandbox approach. 2. uBlock Origin full capability: Firefox MV3 still supports blocking webRequest API. Chrome’s MV3 restricts this, weakening uBlock’s dynamic filtering. If you use uBlock advanced mode, Firefox is the only major browser where it works fully. 3. DNS over HTTPS with Trusted Recursive Resolver: Firefox’s DoH operates independently of OS DNS, with a stricter privacy agreement with Cloudflare/NextDNS than Chrome’s DoH implementation. 4. Root certificate store: Firefox uses its own NSS store (not OS). Corporate proxies can’t silently MITM your HTTPS traffic without explicitly adding their cert to Firefox (unlike Chrome, which inherits OS-trusted certs automatically). 5. WebRTC IP: in about:config prevents WebRTC from leaking LAN IPs. Chrome has no equivalent. These aren’t user-visible UX differences — they’re architectural. For developers building privacy-sensitive apps, they matter.