Prefer:Safe — Making Online Safety Simpler in Firefox

Alex Fowler

Mozilla believes users have the right to shape the Internet and their own experiences on it. However, there are instances when people seek to shape not only their own experiences, but also those of young users and family members whose needs related to trust and safety may differ. To do this, users must navigate multiple settings, enable parental controls, tweak browsers and modify defaults on services like search engines.

We’re pleased to announce a smart feature in Firefox for just this type of user called Prefer:Safe, designed to simplify and strengthen the online trust and safety model. Developed in collaboration with a number of leading technologists and companies, this feature connects parental controls enabled on Mac OS and Windows with the sites they visit online via their browser.

How it works:

  • Users on Mac OS and Windows enable Parental Controls.
  • Firefox sees that the user’s operating system is running in Parental Control mode and sends a HTTP header — “Prefer:Safe” — to every site and service the user visits online.
  • A site or service looking for the HTTP header automatically supports higher safety controls it makes available, including honoring content or functionality restrictions.
  • Users won’t find any UI in Firefox to enable or disable Prefer:Safe, which becomes one less thing for kids to try to circumvent to disable this control.

Prefer:Safe demonstrates the power and elegance of HTTP headers for empowering users to communicate preferences to websites and online services. This is one reason we’ve been championing Do Not Track, which is a HTTP header-based privacy signal for addressing third-party tracking under development at the W3C. In this case, no other configurations are necessary at either the browser or search engine level for this user preference to be effective across the Web, which helps ensure the intended online experiences meet user expectations.

We’re pleased that Internet Explorer has implemented this feature for their users, which along with Firefox, makes this capability relevant at scale right out of the box. We hope to see broader adoption of this feature in the near future.

For more information about Prefer:Safe, a draft specification has been submitted to the IETF. To discuss this feature, I’ve cross-posted this to Mozilla’s Dev.Privacy group.