Trackers and adtech companies have long abused browser features to follow people around the web. Since 2018, we have been dedicated to reducing the number of ways our users can be tracked. As a first line of defense, we’ve blocked cookies from known trackers and scripts from known fingerprinting companies. In Firefox 85, we’re introducing a fundamental...

Background Two years ago, we announced experimental support for the privacy-protecting Encrypted Server Name Indication (ESNI) extension in Firefox Nightly. The Server Name Indication (SNI) TLS extension enables server and certificate selection by transmitting a cleartext copy of the server hostname in the TLS Client Hello message. This represents...

Firefox is the only major browser that still evaluates every website it connects to whether the certificate used has been reported as revoked. Firefox users are notified of all connections involving untrustworthy certificates, regardless the popularity of the site. Inconveniently, checking certificate status sometimes slows down the connection to websites....

Overview The Domain Name System (DNS) is often referred to as the “phonebook of the Internet.” It is responsible for translating human readable domain names–such as mozilla.org–into IP addresses, which are necessary for nearly all communication on the Internet. At a high level, clients typically resolve a name by sending a query to a recursive resolver,...

  Security on the web matters. Whenever you connect to a web page and enter a password, a credit card number, or other sensitive information, you want to be sure that this information is kept secure. Whether you are writing a personal email or reading a page on a medical condition, you don’t want that information leaked to eavesdroppers on the network...

Throughout 2020, Firefox users have been seeing fewer secure connection errors while browsing the Web. We’ve been improving connection errors overall for some time, and a new feature called Intermediate Certificate Authority (CA) Preloading is our latest innovation. This technique reduces connection errors that users encounter when web servers forget...