Waterfox

What Is Waterfox?

In 2011, a sixteen-year-old in the UK named Alex Kontos started building a 64-bit version of Firefox in his spare time, frustrated that Mozilla's official build was still 32-bit. He called it Waterfox, hosted it on a personal site, and posted about it on a few forums. Within a year, the browser had a small but serious following of power users who wanted Firefox without the telemetry. Within five years, that following had grown into one of the most-used independent browsers in the world.

In December 2019, Kontos sold Waterfox to System1, a US advertising company that had also recently acquired Startpage and other privacy properties. The thesis was reasonable on paper: System1 had the resources to fund a small browser team, Kontos would stay as lead developer, and the product would gain financial stability. The reality, by 2023, was different. System1's strategic priorities were advertising, not browser engineering, and the privacy-first vision Kontos had spent a decade building was increasingly hard to defend inside an ad-tech corporate structure. On 3 July 2023, Kontos announced he had bought Waterfox back from System1 and re-incorporated it as a fully independent UK company, Waterfox Limited (Companies House: 08071145).

That buyback is the story behind the current product. Waterfox in 2026 is a small, founder-controlled, independent UK browser project — no advertising revenue, no venture capital, no corporate parent. The codebase is MPL 2.0 open source on GitHub. The funding is bootstrapped via voluntary contributions and a Waterfox Private Search subscription. For users who want a Firefox-compatible browser with the telemetry surgically removed and the founder still answering issues himself, that's exactly the proposition.

Key Features

Zero-Telemetry by Architecture, Not Configuration

Waterfox's most fundamental differentiator is the absence of data collection. Mozilla's Firefox includes telemetry on by default — crash reports, usage statistics, A/B experiment data, and personalisation feeds — and even with the privacy settings dialled to maximum, several data streams remain. Waterfox removes these at the source-code level. There is nothing to opt out of because the data collection code is not present in the build.

This matters for users in regulated industries, journalists handling sensitive sources, and anyone who has read enough breach notifications to mistrust opt-out privacy. The source code is publicly auditable on GitHub under the BrowserWorks organisation, so the claim is verifiable rather than asserted. For a browser to make this claim while remaining compatible with the Firefox extension ecosystem is technically uncommon.

Oblivious DNS Enabled by Default

Standard DNS resolvers can see every domain a user visits and the IP address asking. Even DNS-over-HTTPS, which encrypts the query in transit, still reveals to the resolver who is asking. Oblivious DNS, an emerging IETF standard, splits these two pieces of information across two servers so that no single party knows both who is asking and what they are asking about.

Waterfox enables oblivious DNS by default. Most browsers leave DNS configuration to the operating system, which means most users get whatever their ISP provides — typically unencrypted and observable. Waterfox's default-on choice removes a category of passive surveillance without requiring the user to configure anything.

Tree-Style Vertical Tabs Built In

Power users who run dozens of tabs in research-heavy workflows have historically depended on the Tree Style Tab extension for Firefox. Since version 6.6.0, Waterfox includes this functionality natively — vertical tab orientation, automatic parent-child relationships when a link opens a new tab, and collapsible groups. No extension installation, no maintenance burden when extensions break after a Firefox update, and tighter integration with the browser chrome.

For users who think in trees rather than rows, this is the kind of small thing that disproportionately affects daily productivity. Combined with Private Tabs (per-tab isolated incognito sessions), the tab management story is genuinely better than vanilla Firefox.

AI-Free by Design

Mozilla, Microsoft, and Google have all added AI sidebars, Copilot integrations, and chat assistants to their browsers in 2025–2026. Waterfox has explicitly declined to follow. There is no AI sidebar, no chat panel, no upsell for an AI subscription embedded in the browser chrome. For users who want a browser that browses websites without an additional generative-AI surface area attached, this is increasingly hard to find.

Pricing

Waterfox is free and open source under the Mozilla Public License 2.0. There is no paid tier of the browser itself. The funding model is voluntary: users who appreciate the project can donate, and Waterfox offers an optional subscription for Waterfox Private Search — a meta-search service that sits outside the browser and provides search results without tracking the user.

For a browser project, this funding model is honest about its constraints. It also means there is no enterprise SLA, no paid support contract, and no managed deployment package. Users get the project for free and the project survives on goodwill and the Private Search subscription. That trade-off is worth understanding before recommending Waterfox to a corporate IT department.

EU Compliance and Privacy

Waterfox is registered as Waterfox Limited in the United Kingdom (Companies House number 08071145). Following Brexit, the UK operates under UK GDPR, which mirrors EU GDPR requirements closely and remains covered by an EU adequacy decision as of this review. For UK and EU users, the legal jurisdiction is appropriate.

The deeper compliance story is architectural rather than contractual. A browser that does not collect data does not have GDPR data-handling exposure to manage. Waterfox does not run analytics, does not transmit usage statistics, and does not store user behaviour data on its own servers. The browser also does not embed advertising or third-party trackers in its default configuration. This means the GDPR risk surface for a Waterfox user is essentially zero, which is a stronger position than most browsers can claim regardless of where they are headquartered.

For users who want maximum verifiability, the open-source codebase under MPL 2.0 means the privacy claims can be independently audited rather than taken on trust.

Who It's Best For

Privacy-conscious individuals who want a Firefox-compatible browser with all telemetry, experiments, and personalisation feeds removed at the source. Waterfox provides this without requiring extensive configuration of opt-out settings.

Power users with tab-heavy workflows who have historically depended on extensions like Tree Style Tab. Waterfox bakes vertical tree tabs into the browser itself, removing the maintenance burden of an extension that breaks after major Firefox updates.

Open-source advocates who want their browser to be auditable rather than asserted. Waterfox's MPL 2.0 codebase on GitHub is reviewable, and the founder-controlled UK company structure means there is no ad-tech parent to compromise the privacy stance.

Waterfox is less suited for IT teams deploying browsers across hundreds or thousands of corporate devices. The very small team size means there are no enterprise SLAs, no centralised policy management tools, and no vendor-backed support contracts. Firefox ESR, Chrome Enterprise, or Edge for Business are more appropriate for managed corporate deployments.

The Verdict

Waterfox does one thing exceptionally well: it provides a Firefox-compatible browser with all data collection removed at the source level, and it does so under a UK-registered, founder-controlled, independent corporate structure. The native tree vertical tabs, default-on oblivious DNS, and explicit refusal to add AI chat sidebars give it a clear product identity that mainstream browsers have moved away from. The trade-offs are real — slow release cadence, no enterprise support, smaller team than well-funded competitors, and dependence on voluntary funding — but for individual privacy-focused users and small teams, Waterfox represents the closest thing in 2026 to "Firefox the way you remember it" with credible long-term independence.

Frequently Asked Questions

Is Waterfox truly private — does it send any data to the company?

Waterfox is designed with zero telemetry as a core principle, not an opt-in. Unlike Firefox, which collects crash reports, usage statistics, and A/B experiment data by default, Waterfox ships with all such data collection removed at the source level. The browser does not send analytics, does not run remote experiments, and does not include personalisation feeds. The oblivious DNS feature, enabled by default, prevents DNS resolvers from linking your IP address to your queries. For users who want to verify these claims, the source code is publicly available under MPL 2.0 on GitHub at BrowserWorks/waterfox.

What happened with the System1 acquisition and why is Waterfox independent again?

Alex Kontos created Waterfox in 2011 at age 16, growing it into one of the most popular Firefox forks. In December 2019 (announced February 2020), he sold Waterfox to System1, a US-based search advertising company, while remaining lead developer. By 2023, the strategic direction had diverged significantly: System1 was an advertising business with limited appetite for the privacy-focused browser vision Kontos had. On 3 July 2023, Kontos announced Waterfox had parted ways with System1 and was once again a fully independent project under Waterfox Limited, a UK company (Companies House: 08071145). The buyback restored full editorial and technical independence.

Does Waterfox support Chrome or Firefox extensions?

Waterfox supports Firefox extensions from the official Mozilla Add-ons (AMO) marketplace, including uBlock Origin, Bitwarden, Privacy Badger, and 1Password. It does not support Chrome Web Store extensions directly, as Waterfox is Gecko-based rather than Chromium-based. The vast majority of privacy-focused and productivity extensions are available via AMO. Waterfox Classic, which previously supported legacy XUL extensions from the pre-Firefox 57 era, reached its final release in November 2022 and is no longer actively maintained.

How does Waterfox differ from Firefox and Brave?

Firefox is Mozilla's mainstream browser with telemetry, A/B experiments, and optional AI features enabled by default. Waterfox is a Firefox fork with all telemetry stripped and power-user features like tree vertical tabs added natively, but without Firefox's marketing budget or team size. Brave is Chromium-based with a built-in ad blocker and optional crypto rewards, giving it Chrome extension compatibility and a larger commercial operation. Waterfox's differentiators are its zero-telemetry stance, Gecko engine (meaning Firefox extension compatibility rather than Chrome extensions), native tree tabs, and its independent UK-registered structure with no venture capital or advertising revenue.

Is Waterfox suitable for business or enterprise use?

Waterfox is well suited for privacy-conscious individuals and small teams who want a Firefox-compatible browser with no data collection. For enterprise deployment, the very small team size (Waterfox Limited is a micro-business) means there are no formal SLAs, enterprise support contracts, or managed deployment tools comparable to Firefox ESR, Chrome Enterprise, or Edge for Business. IT teams requiring centralised policy management, device enrolment, or vendor-backed support are better served by Firefox ESR or a Chromium-based enterprise option. Waterfox is strongest as a personal productivity and privacy tool rather than a managed corporate deployment.