Mozilla

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Mozilla

Basic information
Founded	1998
Type	Private
Industry	Open Source Software, Advertising
Official website	https://www.mozilla.org/

Mozilla is a free software community which develops, publishes and supports open source software. The community is supported institutionally by the non-profit Mozilla Foundation and its tax-paying subsidiary, the Mozilla Corporation.

Consumer impact summary

Mozilla Manifesto

Mozilla has published the community Manifesto, with 10 key principles:

1. The internet is an integral part of modern life—a key component in education, communication, collaboration, business, entertainment and society as a whole.
2. The internet is a global public resource that must remain open and accessible.
3. The internet must enrich the lives of individual human beings.
4. Individuals’ security and privacy on the internet are fundamental and must not be treated as optional.
5. Individuals must have the ability to shape the internet and their own experiences on the internet.
6. The effectiveness of the internet as a public resource depends upon interoperability (protocols, data formats, content), innovation and decentralized participation worldwide.
7. Free and open source software promotes the development of the internet as a public resource.
8. Transparent community-based processes promote participation, accountability and trust.
9. Commercial involvement in the development of the internet brings many benefits; a balance between commercial profit and public benefit is critical.
10. Magnifying the public benefit aspects of the internet is an important goal, worthy of time, attention and commitment.

Incidents

Removing "We don't sell your data" promise

In February 2025, Mozilla started to delete references to their "We don't sell your data" promise from the source code, as first reported by Haiku operating system developer waddlesplash on the forum thread for their Firefox/Iceweasel port.

They also switched the wording from "The best privacy" to "Always protected".

Introducing TOS for Firefox (2025)

Main article: Mozilla introduces TOS to Firefox

Important: This situation is ongoing so the full impact to consumers has yet to be determined

In February 2025 Mozilla introduced terms of use (TOS) for the Firefox browser for the first time as well as an updated privacy policy. The new privacy policy has caused concern among the browser's user revolving around the way the section that describes the rights Mozilla has over their data is phrased.

Privacy-preserving attribution

Privacy-preserving attribution (PPA) is an experimental feature introduced in Firefox version 128, designed to help advertising sites measure the performance of their ads while maintaining user privacy. It is marketed as an alternative method for performing attribution without relying on online tracking of users' browsing activity, which is incompatible with privacy. The functionality is explained on the Mozilla support page as follows:

1. Websites that show you ads can ask Firefox to remember these ads. When this happens, Firefox stores an “impression” which contains a little bit of information about the ad, including a destination website.
2. If you visit the destination website and do something that the website considers to be important enough to count (a “conversion”), that website can ask Firefox to generate a report. The destination website specifies what ads it is interested in.
3. Firefox creates a report based on what the website asks, but does not give the result to the website. Instead, Firefox encrypts the report and anonymously submits it using the Distributed Aggregation Protocol (DAP) to an “aggregation service”.
4. Your results are combined with many similar reports by the aggregation service. The destination website periodically receives a summary of the reports. The summary includes noise that provides differential privacy.

Browsing activity information is not sent to anyone, not even Mozilla. However, users with PPA enable must rely solely on the company to honor principle number 4 in its Manifesto.

PPA does not involve sending information about your browsing activities to anyone. This includes Mozilla and our DAP partner (ISRG). Advertisers only receive aggregate information that answers basic questions about the effectiveness of their advertising.

This feature does not allow users to make an informed decision and choose whether to opt-in or not, as it is enabled by default and requires opting out. This goes against principle number 8 of the Manifesto.

Anonym acquisition

Mozilla becomes an advertiser by acquiring Anonym going against their mission of being a proponent of privacy.

Mr Robot promotional web extension

In December 2017 Mozilla, in collaboration with the Mr Robot team, created and included by default a web extension in firefox named "looking glass", while being disabled by default many users where confused and worried to discover a unknown extension installed in their browser with a cryptic description "MY REALITY IS JUST DIFFERENT THAN YOURS." which was later expended later to include references to Mozilla's collaboration

The extension when activated execute code on all websites visited by the user, searching for all words matching a list, every words matched were wrap into HTML span tags, tooltips were injected to be display when the user over these words, CSS code was injected to make the words appears upside down and the tooltips work. Also three specific website did have their header changed to have a value "x-1057" injected.

While the extension could in rare occasion break some website with the HTML and CSS injection, it did not do anything malicious or dangerous, the extension was not collecting any personal information at all which Mozilla qualified a mistake in their response addressing the issue

A SHIELD study must be designed to answer a specific question. We evaluated Looking Glass based on whether or not it upheld user privacy. Since it did not collect any data, we felt that it was safe. In retrospect, not capturing data was a strong indicator that this was not a good SHIELD study candidate, so we’re making sure we’re going to specifically evaluate future studies based on this criteria to ensure that we don’t repeat our mistake.