Waterfox

Description

Alex Kontos was 16 years old in March 2011 when he created the first version of Waterfox. At the time, Firefox was still 32-bit only, and Kontos wanted a 64-bit build that could use his hardware properly. He published it online and discovered he was not the only one wanting that. Waterfox grew from there.

The original goal was performance. Over time, privacy also became equally central. Waterfox is now a free, open-source browser based on Mozilla’s Firefox codebase, and it takes a specific position: strip out everything Firefox includes that serves Mozilla’s interests rather than the user’s, keep everything that makes Firefox a good browser, and add back customization features that Firefox has removed over the years.

Waterfox is built on the Extended Support Release branch of Firefox, instead of the rapid-release channel. That means there are fewer frequent updates but they are stable longer. The current base is Firefox ESR 140, which Waterfox adopted with the 6.6.x series in August of 2025.

The ownership of the browser has changed twice. In December 2019, Kontos sold Waterfox to System1, an advertising technology company. Privacy-minded users understandably were not so comfortable. In July 2023, Waterfox again became independent under a new entity called Waterfox, Inc. Kontos remains at the helm.

PRIVACY

The central premise of Waterfox is that Firefox gathers more information about users than users know or consent to. Waterfox solves this at the build level instead of with settings toggles.

Waterfox removes telemetry completely during compilation — it doesn’t even exist in the binary, not just disabled. Firefox’s A/B testing framework, remote experiments, personalization feeds, sponsored content, and the geo-IP lookup that Firefox runs on first launch to determine the user’s region are all gone. Waterfox relies on bundled configuration lists that are downloaded offline instead of retrieving settings from Mozilla’s servers. This removes the network calls that Firefox makes to Mozilla infrastructure in the background during normal browsing.

Enhanced Tracking Protection, inherited from Firefox, blocks third party tracking cookies, social media trackers, cryptominers, and known fingerprinting scripts via Disconnect.me’s filter lists. Standard mode covers the most common cases. Strict mode is more general blocking, including suspected fingerprinting vectors.

For DNS, Waterfox ships Oblivious DNS over HTTPS using Fastly’s infrastructure. Standard DoH encrypts DNS queries, but still reveals who is asking to the resolver. ODoH inserts a proxy layer between the user and resolver (the resolver can see the query, but not who sent it, and the proxy can see the user but not what the query is). The combination is that neither party has both pieces of information.

Waterfox also removes URL tracking parameters prior to sharing links, isolates browsing sessions via Container Tabs, and disables all of Firefox’s AI features – link previews, chatbot integrations, and the on-device ML runtime.

INTERFACE

Waterfox re-enables several interface elements that Firefox has removed, retired or hidden behind settings that most users will never discover.

The status bar is back. This appears at the bottom of the window and displays the URL of any link that is hovered over. Users can also add widgets to it — extension icons, a bookmark counter, or other tools — through inbuilt settings.

Tab bar positioning is flexible. Users can drag the tab bar up or down the address bar, or to the bottom of the window entirely. The bookmarks bar also moves between the top and bottom. Tab shapes, spacing, separators and favicon display can all be changed without needing to touch anything in about:config or install an extension.

Vertical Tabs in the sidebar bring the tab list to the left side of the browser. Waterfox has two variants. The standard layout is a vertical list of all open tabs. Tree-Style mode goes even further: tabs that are opened from a link become child tabs, indented beneath the parent tab that opened them. The hierarchy changes as the user is browsing. Firefox users have been asking for this for years; third-party extensions such as Tree Style Tab had it, but Waterfox has it built in natively.

Tab Groups group tabs into named, color-coded groups that collapse into a single item, to help reduce visual noise. Manual tab unloading releases the memory a tab is holding without closing it; unloaded tabs show a wireframe preview of what was last loaded in them as a reminder of what was there.

The new tab page supports wallpapers — solid colors, custom hex values, or user-supplied images. The preferences page contains a table of contents. The legacy password manager is still available at about:passwords. The classic config manager lives at approximately:cfg. Windows builds include the Visual Studio redistributables bundled in such a way that Waterfox will run on a clean install. Apple included Waterfox to the iCloud Passwords browser whitelist in December 2025. The Flathub store has a verified Flatpak. Windows builds support Mica backdrop effects and macOS builds integrate with the system titlebar appearance.

One less obvious setting to mention: Waterfox disables address bar speculative connections. Firefox usually makes background DNS lookups and connection attempts while the user is typing, attempting to pre-load likely destinations. Waterfox disables this, and that means no network requests are sent out until the user actually presses Enter.

EXTENSIONS

Waterfox accepts extensions from three sources simultaneously: Mozilla’s add-ons store at addons.mozilla.org, the Chrome Web Store and the Opera Extensions store. No configuration required — all three work out of the box. Classic-style extensions based on older Firefox extension APIs continue to function here, TabMixPlus being one example. Extensions can also be installed directly from .xpi files.

SEARCH

Startpage is the default search engine for desktop. It retrieves Google results without passing the user’s identity to Google — the results come from Google, but Google doesn’t see who asked. Ecosia is the default on Android, it uses its ad revenue to finance climate and biodiversity projects. Mojeek and Qwant are also available in the default engine list.

Waterfox Private Search was released in 2025 as an optional subscription service at search.waterfox.net. It’s a meta-search engine — it searches several sources and aggregates the results — with no tracking, no advertising, and no AI-generated summaries. Users can call it using the @wps alias in the address bar.

ANDROID

Waterfox for Android was introduced to Google Play in November 2023. In 2025, the team reworked it from scratch on the ESR 140 codebase, compiling Android Components, Gecko, and SpiderMonkey from source. Like the desktop version, the Android build strips out telemetry, sponsored content and experiment systems entirely.

The Android version supports the full Mozilla Add-ons catalog, custom AMO collections and direct .xpi installs. Standard Firefox for Android is more restricted in what extensions it will allow; Waterfox is not. ODoH Ultra Protection mode is available to DNS. Full about:config access is provided. An OLED optimized black theme helps reduce the battery drain on OLED displays.

WATERFOX CLASSIC

Waterfox Classic was a separate branch based on Firefox 56 — the last version before Mozilla removed support for legacy XUL and XPCOM add-ons in 2017. Some extensions never migrated to the new API and Classic kept them alive. It was finally released in November 2022 and is not under active development anymore. It contains a number of security vulnerabilities that have not been patched. Anyone still running it should either migrate to current Waterfox or just accept that the browser does not receive any security fixes.