Browsers

Web tracking relies on four main signals:

• Cookies and site storage. Data a site, or a third party embedded in it, stores in your browser to recognise you later. Privacy-focused browsers partition third-party storage per site, but logins and first-party cookies still identify you.
• Your IP address. Every server you contact sees it, and it is often enough to place you in a household or town. A browser setting cannot hide it; Tor or a VPN can.
• Fingerprinting. Scripts read your screen and window size, time zone, language, installed fonts, graphics hardware and many other details. Combined, these are often unique enough to recognise your browser without storing anything on it, which is why clearing cookies does not help.
• Accounts and sync. Signing in to the browser itself, for example with a Google or Microsoft account, links your browsing to an identity held by the vendor.

Fingerprinting matters more as cookie tracking gets harder. Since 16 February 2025, Google's advertising policies no longer prohibit advertisers from fingerprinting users; the UK data protection regulator called the change "irresponsible" (ICO statement).

Why blending in matters

There are two ways to resist fingerprinting. Uniformity, used by Tor Browser and Mullvad Browser, makes users report the same values wherever possible (a rounded window size, a standard font set, UTC as the time zone), so you hide in a crowd. Randomisation, used by Brave and some Chromium forks, feeds each site slightly different noise per session, so the values a tracker collects do not stay stable. Both work best when you leave the defaults alone.

Every change you make (an extra extension, a non-default setting, an unusual window size) can split you off from the crowd. A rare, heavily customised browser can stand out more than a common one with modest settings. This is why the browsers recommended below ask you not to customise them, and why piling extensions onto a normal browser often backfires.

These browsers resist fingerprinting or exploitation by default and send little or nothing to their developers. Use them with their default settings.

Why Chromium-based browsers are safer on Android

On Android the engine underneath matters for security. Chromium has the stronger sandbox, and Vanadium adds strict site isolation, which puts each site in its own sandboxed process. GrapheneOS's developers state that "Firefox does not have internal sandboxing on Android" and that Gecko-based browsers are more exposed to exploitation (GrapheneOS usage guide). Stock Firefox for Android still offers site isolation only as an opt-in Labs toggle, off by default as of version 155 (report, September 2026); IronFox enables it.

In practice: on GrapheneOS, use Vanadium for everyday browsing. On other Android phones there is no option without trade-offs: IronFox for privacy defaults, or a Chromium-based browser such as Brave or Cromite for stronger sandboxing (see their cons below). Use Tor Browser for Android when you need to hide your IP address. More on phone operating systems in the OS guide.

iPhone and iPad

There is no Tor Browser for iOS. The Tor Project points iPhone users to Onion Browser, which routes traffic over Tor, but says Apple's requirement that iOS browsers use the WebKit engine prevents it from offering the same protections as Tor Browser. If you need strong browser privacy, do that browsing on a desktop or an Android device.

Better than mainstream browsers, but each has a real gap: weaker or optional fingerprinting protection, slow or manual security updates, or bundled features you need to switch off.

Stock Firefox is listed here because of what it collects and promotes by default. Its engine is the base of Tor Browser, Mullvad Browser, LibreWolf and IronFox, which remove most of these issues, and it can be hardened (see practical tips).

Google Chrome and Microsoft Edge are not covered in detail. Both come from companies with large advertising businesses, encourage signing in with a Google or Microsoft account, and have dropped (Chrome) or are dropping (Edge) the extension format that full uBlock Origin needs.

Extensions can read and change every page you visit, so each one is a trust decision. Install as few as possible. In Tor Browser and Mullvad Browser, add none: the bundled ones are already configured, and anything extra makes you stand out.

Chrome no longer runs full uBlock Origin

Google has finished removing Manifest V2, the extension format that powerful content blockers rely on. Chrome 138 (July 2025) disabled Manifest V2 extensions, Chrome 139 removed support, and on 31 August 2026 all remaining Manifest V2 extensions, uBlock Origin among them, were taken off the Chrome Web Store (Google timeline, CyberInsider). Chrome users are left with uBlock Origin Lite, a less capable Manifest V3 version. Microsoft has started the same transition in Edge, showing deprecation warnings since September 2026 (Microsoft timeline). Firefox and its forks still run full uBlock Origin, and Brave hosts its own copies of uBlock Origin, NoScript, uMatrix and AdGuard.

• Choose by threat. Tor Browser when you need to hide who you are; Mullvad Browser with a VPN for private browsing without accounts on desktop; a hardened Firefox fork or Brave when you need logins and site compatibility.
• Separate your identities. Use different browsers or profiles for logged-in accounts and for anonymous browsing, so cookies and fingerprints cannot link them. The alting guide covers running separate identities.
• Delete cookies and site data when the browser closes, with exceptions only for the few sites you log into regularly.
• Do not save passwords in the browser. Use a dedicated password manager instead.
• Avoid signing in to the browser itself. Sync links your browsing to an account held by the vendor.
• Check for WebRTC leaks. WebRTC can reveal your real IP address even behind a VPN (ungoogled-chromium FAQ). Test after connecting your VPN, and use encrypted DNS as well (DNS guide).
• If you use Firefox, consider arkenfox. It is a maintained template of privacy settings. Read its wiki first: some settings break sites, and you need to understand what you are changing.
• Leave Tor Browser and Mullvad Browser alone. Keep the default window size, do not add extensions, and use the preset security levels instead of individual tweaks, which can put you in a small "Custom" group.
• Update promptly. Browser vulnerabilities are patched constantly. Browsers without auto-update (LibreWolf, ungoogled-chromium, Cromite on desktop) need you or your package manager to keep up.

• Treating private or incognito mode as anonymity. It only stops your own device from keeping history. Sites still see your IP address and fingerprint.
• Installing many privacy extensions. Each one adds attack surface and makes your browser rarer. GrapheneOS's developers recommend against "piling on browser extensions and modifications" (source).
• Customising Tor Browser or Mullvad Browser. Their protection depends on you looking like every other user.
• Mixing identities in one browser. Logging into personal accounts in the same browser you use for anonymous research links the two, whatever VPN you use.
• Handing sensitive browsing to an AI assistant. AI sidebars and agent modes, such as Firefox's Smart Window, Brave's Leo and Perplexity's Comet, can send page content to cloud models, and agents can be steered by instructions hidden in web pages. Brave's researchers showed such an attack against Comet in 2025 (Brave). Keep these features off for sensitive work; see the AI guide.

• EFF: Cover Your Trackscoveryourtracks.eff.orgSee how trackers see your browser.
• Tor Project: anti-fingerprintingsupport.torproject.orgHow Tor Browser reduces the number of distinguishable groups.
• Mullvad Browser: hard factsmullvad.netWhat the browser changes, connects to and disables.
• GrapheneOS: web browsinggrapheneos.orgBrowser security on Android, from the GrapheneOS developers.
• Why uBlock Origin works best on Firefoxgithub.com
• ICO: response to Google allowing fingerprintingico.org.uk