Device & System

What your browser exposes about the machine you're running on.

IP …
Location …
ISP …
ASN …

Screen & Display

Color key Green — healthy / above target Blue — normal / neutral info Amber — below target, worth a look Red — leak or serious problem Grey — not run yet

Screen size, density, color depth, and platform.

window.screen + devicePixelRatio + navigator.platform + maxTouchPoints.

Fix this

CPU / Memory / Battery

Color key Green — healthy / above target Blue — normal / neutral info Amber — below target, worth a look Red — leak or serious problem Grey — not run yet

How much horsepower your device reports.

hardwareConcurrency, deviceMemory, Battery API status.

Fix this

Plugins & MIME

Color key Green — healthy / above target Blue — normal / neutral info Amber — below target, worth a look Red — leak or serious problem Grey — not run yet

Legacy plugins and supported media types.

navigator.plugins + mimeTypes enumeration.

Fix this

Screen & Display

What is this?

Every browser exposes the pixel dimensions of your screen (window.screen.width and height), the color depth, the pixel density (devicePixelRatio), the OS platform (navigator.platform), and whether you have a touch screen (navigator.maxTouchPoints). Websites use these values for legitimate reasons -- picking the right image resolution, deciding whether to show a mobile layout -- but the same values are also the top three contributors to a browser fingerprint, right up there with fonts and canvas rendering. A specific combination like 3840x1080 at 1x with Win32 and no touch is unusual enough that it narrows the room of potential users you could be by a huge factor.

So what?

Fingerprinting is how ad networks and fraud-detection systems track you across sites even when you clear cookies and use private browsing. Your IP might rotate, your cookies might reset, but your screen resolution + platform + touch capability rarely change from one session to the next. That is why hardened browsers like Brave, LibreWolf, and Tor Browser deliberately misreport these values -- they clamp the resolution, force devicePixelRatio to a common value, and lie about touch support so every user on that browser looks the same to fingerprinters.

Now what?

If fingerprint resistance matters, switch to Brave, LibreWolf, or Tor Browser. Chrome, Edge, and Safari expose these values with no way to hide them.

Deep dive tutorial Screen and display fingerprints, and how to blend in Back to top

CPU / Memory / Battery

What is this?

Three separate APIs are being probed here. navigator.hardwareConcurrency returns the number of logical CPU cores your OS reports (usually 4, 8, 12, or 16 on modern hardware). navigator.deviceMemory returns your RAM rounded to a power of 2 in gigabytes (0.25, 0.5, 1, 2, 4, 8) -- yes, only Chromium browsers ship this, and yes, it caps at 8 GB even if you have 128 GB. navigator.getBattery() returns your battery level and charging state (also Chromium-only since Firefox removed it in 2021 and Safari never had it). Together these three values are a shockingly specific fingerprint: an 8-core / 8 GB / 47%-battery-and-charging profile is unusual enough that ad networks can re-identify the same laptop across sites and even across browser reloads.

So what?

The Battery API is the most notorious of the three -- it was deliberately removed from Firefox because researchers proved you could track a specific device across sessions just by watching the battery percentage drift by 1-2% every few minutes. Chrome kept it. Cores + memory together give roughly 6 bits of fingerprinting entropy, meaning they cut the anonymity set by a factor of 64 -- combine that with your screen resolution (another 6+ bits) and your user agent (another 4+ bits) and you are down from "one in a billion users" to "one in a few dozen" before any tracker even looks at cookies.

Now what?

If cores + memory + battery are all exposed, switch to Brave or Firefox. Chrome and Edge have no built-in way to hide these.

Deep dive tutorial CPU, memory, and battery: your hardware fingerprint Back to top

Plugins & MIME

What is this?

navigator.plugins is a legacy API from the Flash / Java Applet era that lists every browser plugin currently loaded. Modern browsers no longer run real plugins, but they still return a fixed list of built-in PDF viewer entries (PDF Viewer, Chrome PDF Viewer, Chromium PDF Viewer, Microsoft Edge PDF Viewer, WebKit built-in PDF) to avoid breaking old sites. Those five entries are identical for every user of a given browser, so they are non-identifying. Anything OUTSIDE that fixed list -- extension-injected entries, legacy NPAPI leftovers, custom PDF handlers -- is unique to you and adds real fingerprinting entropy.

So what?

Even one non-standard plugin name in your list can be enough to single you out. Ad networks and fraud-detection systems hash the full plugin list and use it as a stable identifier -- your cookies can reset, your IP can rotate, but if your plugin fingerprint stays the same you are still recognizable. The scarier version: some browser extensions inject their name directly into navigator.plugins as a side-effect of their functionality, which means installing a niche privacy extension can actually make you MORE identifiable, not less. Chrome standardized to always return the same 5 PDF entries specifically to close this hole, and Firefox followed suit.

Now what?

If non-standard plugins show up, audit your browser extensions and disable everything you do not actively use. For anonymous sessions, use a browser profile with no extensions or Tor Browser.

Deep dive tutorial Browser extensions: when a privacy tool makes you MORE unique Back to top