The Tor Project announced that it’s working with Mozilla to integrate Tor into Firefox. Eventually, this should completely eliminate the need for the Tor Browser, as most of its features would be merged into Firefox’s new “super-private mode.”

Tor Browser Development Largely Redundant

The Tor Browser is based on the Extended Support Release (ESR) version of Firefox, because it’s a more stable development cycle that only patches bugs and doesn’t add new features for 11 months or so. This means it doesn’t disrupt how the Tor Browser works too much, and the Tor Project developers don’t have to integrate many new features into their browser every few weeks.

Despite this, the Tor Project developers said that it takes a lot of time to rebase Tor Browser patches to new versions of Firefox. This is why Mozilla has started integrating Tor’s patches into Firefox on its own through the “Tor Uplift Project.”

Firefox has also adopted new security features from the Tor Browser such as first party isolation (which prevents cookies from tracking you across domains) and fingerprint resistance (which blocks user tracking through canvas elements). However, first party isolation is off by default in Firefox and fingerprint resistance can break some websites. You can enable first party isolation in about:config or by installing this add-on for it.

Enter Project Fusion

The Tor Project developers said that the main objectives of Project Fusion are:

Fingerprinting resistance, make more user friendly and reduce web breakage

Implement proxy bypass framework

Figure out the best way to integrate Tor proxy into Firefox

Real private browsing mode in Firefox: Will turn on First Party Isolation, Fingerprinting Resistance, and Tor proxy

The developers said all these features would enable a “real” private mode in Firefox, which could completely replace the need for the Tor Browser to exist.

This “super-private mode” could be used by hundreds of millions of users eventually, which is why Mozilla first needs to ensure that the Tor network can scale with such usage. That means more people will need to run Tor relays. Mozilla may be able to help here by donating money to nonprofits that can run Tor relays.

A Firefox Competitive Advantage

The Tor Project developers said that Project Fusion has the accord of Mozilla’s CEO and CTO, which probably means it has a high chance of coming to fruition. However, many issues have to be considered first, such as developing private telemetry, fixing the problem with fingerprinting resistance breaking websites, and so on.

Additionally, Mozilla wants to first standardize the Tor client specification, write conformance tests for it, and open the documentation. All of that means that more people could look at how Tor is implemented in Firefox and see if there are any issues with that implementation.

The main reason why Mozilla would even want to integrate Tor into Firefox is because it could provide its users real private browsing, something that most competitors will not be able to offer. Mozilla has taken an increasingly strong pro-privacy stance in the past few years, and Project Fusion could further boost its pro-privacy image.

It could also put Firefox in a much more direct contrast with Chrome, a browser developed by Google, which is heavily invested in user tracking in order to serve more targeted ads.