Brave Shields: Standard vs Aggressive and What They Block

Brave Ships With the Blocking Turned On

Brave Shields block trackers, cross-site cookies, phishing, and fingerprinting by default from the first page load, with nothing to install or configure. Shields runs in two modes. Standard (the default) blocks known third-party trackers and cross-site cookies while allowing most first-party cookies through. Aggressive adds first-party cookie partitioning, stricter script blocking, and harder fingerprinting defenses including farbling, which randomizes the signals sites use to identify visitors. Both modes affect how your analytics tags, advertising pixels, and consent banner behave for Brave's users.

How Shields Block Trackers

Brave leans on the same community blocklists ad blockers use, then adds its own. Per Brave, it applies filters from "the EasyList and EasyPrivacy projects, the uBlock Origin project, and lists Brave has generated internally." Known ad and tracker domains are blocked before they load.

On top of the lists, Shields do two structural things:

• Cross-site cookie blocking. Third-party storage is replaced with ephemeral, per-site storage that auto-deletes, so a tracker can't carry an identifier from one site to the next.
• CNAME uncloaking. Like Safari, Brave detects trackers hiding behind a subdomain alias and blocks them anyway, so routing a tracker through track.yoursite.com doesn't slip past.

There are two levels. Standard is the default and aims for the best privacy that still works on most sites. Aggressive applies more protections at a higher risk of breaking pages.

Farbling: Randomizing Your Fingerprint

The part that sets Brave apart is how it handles fingerprinting, the technique of identifying a visitor from the combination of their device and browser characteristics rather than from a cookie. Brave's approach is called farbling: it slightly randomizes the output of semi-identifying browser features, enough to defeat tracking but not enough for a human to notice.

The clever detail is consistency. The randomized values are generated from a per-session, per-site seed, so a single site sees the same fingerprint each time it checks during one session, but a different site sees a different value, and everything reshuffles when the browser restarts. To a fingerprinting script, the same person looks like a different visitor on every site and every session. For the mechanics of why this matters, see Browser Fingerprinting and Why Browsers Block It.

Brave Doesn't Break Your Site

A common worry is that Brave's blocking makes sites unusable, so anything you build gets mangled for those visitors. In practice that's rare, and it helps to know why. Brave is built on Chromium, the same engine as Chrome, so your pages render the way they would in Chrome, minus the trackers. First-party essentials keep working: your login session, shopping cart, language preference, and other functional first-party cookies aren't the target. Shields go after cross-site tracking, not the cookies that make your own site work.

What breaks, occasionally, is a page that genuinely depends on a blocked third party, like an embedded widget served from a tracker domain. Even then, a user can lower Shields for a single site with one click if they want the content. The takeaway for you: design so that core functionality never rides on a third-party tracker, and Brave users get a working site with the tracking stripped out, which is exactly the outcome the browser intends.

What Brave Users Mean For Your Data

Assume that for a Brave visitor on default Shields, most third-party analytics and ad tags never fire, cross-site cookies don't persist, and any fingerprinting-based identification returns randomized, useless values. Your first-party, same-site measurement can still work if the tags aren't on a blocklist, but plan for these users to be substantially invisible to conventional tracking.

That's not a problem to solve so much as a reality to model. Some share of your audience has opted out at the browser level, permanently and by choice. Server-side, consent-based first-party measurement recovers some of it lawfully; nothing recovers all of it, and trying to defeat farbling or unblock Shields would be both futile and hostile to the user.

Related Guides and Sources

Keep reading: Ad Blockers vs Cookie Consent, Safari ITP Explained for Marketers, and Firefox Total Cookie Protection and ETP. Primary source: Brave's Brave Shields documentation, covering the default blocking, filter lists, Standard vs Aggressive modes, and fingerprint randomization.