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Firefox

Firefox is a popular open-source web browser developed by Mozilla.

Privacy Friendly Open Source No Third-Party Trackers Energy Efficient
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Description

Mozilla Firefox is an open-source web browser developed by the Mozilla Foundation, known for its strong focus on user privacy and open web standards. In 2026, Firefox continues to emphasise privacy protections, including Enhanced Tracking Protection, anti-fingerprinting defences. Mozilla is criticised for integrating AI into its Browser, but at least it's claiming to do it in a privacy preserving way.

In 2025, Mozilla faced backlash over updated Terms of Use, which users interpreted as granting broad rights to user data. Mozilla clarified that the terms were intended to formalise existing practices and that user data is not used for AI training or sold to advertisers.

Firefox 145 introduced new anti-fingerprinting defences and PDF annotation tools, but also included optional LLM (AI) integrations, which many criticised as unnecessary bloat.

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Sustainability Features of Firefox

Privacy Friendly - It does not track users unnecessarily.

Firefox’s Enhanced Tracking Protection blocks third-party trackers and fingerprinting scripts by default, especially in Private Browsing Mode and Strict mode.Source: Firefox blocks fingerprinting

Open Source - Free and Open-Source Software

Firefox is fully open-source, allowing for community audits, contributions, and transparency in its development.Source: Github Repo

No Third-Party Trackers - Services that do not use third-party cookies or trackers, ensuring user privacy.

Firefox does not allow third-party trackers in its default browsing experience.Source: Third-party cookies and Firefox tracking protection

Energy Efficient - Hardware or services designed to consume minimal energy, reducing environmental impact.

Firefox’s built-in ad and tracker blocking reduces unnecessary data and energy consumption, making it more efficient for users on limited data plans or battery-powered devices, especially when combined with the uBlock Origin Plugin.

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Summary

Mozilla Firefox remains a leading privacy-focused, open-source browser, offering robust anti-tracking, transparency, and user control. While its commitment to privacy and open standards is strong, recent controversies over data policies and AI integrations have sparked debate among its user base.

Sustainability Score
89

More Sustainable Alternatives in Browser

LibreWolf

LibreWolf is a fork of Firefox, with enhanced security and privacy settings.

LibreWolfs’s built-in ad and tracker blocking reduces unnecessary data and energy consumption. The decision to avoid AI bloat in its browser saves even more resources.
LibreWolf does not allow third-party cookies or share user data with external parties.Source: LibreWolf Features
LibreWolf is fully open-source, allowing for community audits, contributions, and transparency in its development.Source: Codeberg Repos
LibreWolf blocks trackers, ads, and fingerprinting by default, with enhanced protections like uBlock Origin pre-installed and stricter privacy settings.Source: LibreWolf Features
LibreWolf is mostly ad-free, ensuring a cleaner and more private user experience.Source: LibreWolf Features
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Mullvad Browser

Mullvad Browser is privacy-focused with Tor Project Collaboration.

Mullvad is a based in Sweden.
Mullvad’s built-in ad and tracker blocking reduces unnecessary data and energy consumption, making it more efficient for users on limited data plans or battery-powered devices.
Mullvad Browser does not allow third-party trackers or share user data with external parties.
Mullvad Browser removes most ads and sponsored content, ensuring a clean and distraction-free browsing experience.
Mullvad Browser blocks trackers, ads, and fingerprinting by default, with pre-installed uBlock Origin.
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vivaldi logo

Vivaldi

Vivaldi is a highly customisable ad- and AI-free web browser based on Chromium.

Vivaldi Technologies is based in Norway.
By default Vivaldi does not allow third-party cookies.
Vivaldi’s built-in ad and tracker blocking reduces unnecessary data usage and saves energy. Additional energy is saved by avoiding AI bloat in its browser.
Vivaldi blocks ads and trackers by default, with a privacy dashboard for visibility into blocked content.Source: Fighting for a better web
Vivaldi is mostly ad-free, ensuring a cleaner and more private user experience.
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brave logo

Brave

Brave is a privacy-focused web browser based on Chromium.

Brave does not use third-party trackers or allow external parties to collect user data.
Brave’s built-in ad and tracker blocking reduces unnecessary data and energy consumption, making it more efficient for users on limited data plans or battery-powered devices.
Brave blocks ads, trackers, and third-party cookies by default, reducing exposure to online tracking and fingerprinting.
Brave is ad-free by default, ensuring a cleaner and more private user experience.
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