Browser Info - What Your Browser Reveals at a glance
- What it does
- See the user agent, screen size, language, timezone, hardware and battery details your browser exposes to every site you visit. Nothing is recorded.
- Where it runs
- Entirely in your browser — no data is uploaded
- Works offline
- Yes, once the page has loaded
- Cost
- Free, with no account and no usage limit
- Category
- Browser & Network
How to read the report
- Open the page and the report fills in automatically - there is nothing to submit.
- Check the user agent if you are debugging a compatibility problem or a device-detection rule.
- Compare viewport and screen size when a responsive layout breaks on someone's machine but not yours.
- Note the timezone and language, which are the values a site uses to localise dates and currency.
What each field means
| Field | What it tells a site |
|---|---|
| User agent | Browser, engine and operating system, in a string that has accumulated decades of compatibility cruft. Modern browsers deliberately freeze parts of it to reduce tracking. |
| Screen resolution | The physical display size. Distinct from the viewport, which is the area your page actually gets. |
| Viewport size | The visible page area in CSS pixels, after browser chrome and any zoom. |
| Device pixel ratio | How many physical pixels make up one CSS pixel. 2 or 3 on modern phones and Retina displays - it decides whether your images look sharp. |
| Language | Your preferred languages, sent on every request as the Accept-Language header. |
| Timezone | Your IANA timezone name, from the Intl API. Often more precise about your location than an IP lookup. |
| CPU cores | Logical processors available to the page, used to size worker pools. |
| Device memory | An approximate RAM figure, rounded into buckets so it reveals less. |
| Colour scheme | Whether your system is set to light or dark, so sites can match it. |
| Battery | Level and charging state, where the browser still exposes it. Several browsers removed this API precisely because it aided fingerprinting. |
| Cookies enabled | Whether the browser will accept cookies at all. |
| Online status | Whether the browser believes it has a connection. It only detects an interface being up, not whether the internet actually works. |
Why this adds up to a fingerprint
No single value here identifies you. Millions of people share your browser version, and plenty share your screen size. The problem is the combination: browser build, plus screen dimensions, plus timezone, plus installed font list, plus the exact way your graphics hardware renders a test image, produces a signature that is frequently unique.
That signature is stable across sessions and survives clearing cookies and using a private window, which is what makes fingerprinting attractive to trackers and difficult to defend against. The Electronic Frontier Foundation's research on this found that most browsers carried enough entropy to be identified from a handful of properties alone.
Defences that genuinely help: Tor Browser, which makes every user look identical by standardising these values; Firefox's resist-fingerprinting mode; Safari's reduced API surface. Defences that mostly do not: changing your user agent string, which usually makes you more distinctive rather than less.
Why the user agent string looks absurd
A modern Chrome user agent claims to be Mozilla, Gecko, KHTML, Safari and Chrome simultaneously. This is thirty years of compatibility archaeology: each new browser added the identifiers of its predecessors so that servers sniffing for a competitor would still serve it the good version of the page.
The lesson is practical. Do not branch on the user agent string. Feature-detect instead - check whether the API you need exists - because that stays correct as browsers change and does not break for the users you did not anticipate.
What this page does with the values
Nothing. The report is generated by JavaScript in your tab and rendered straight into the page. There is no request to a server, no analytics event carrying these values, and no record of your visit beyond the ordinary web server log that any site keeps.
Frequently asked questions
Yes, for everything listed here. These are properties any script can read. The APIs that do require permission - camera, microphone, precise location, notifications - are not part of this report.
No. A VPN changes the IP address a site sees. It does not touch your screen size, timezone, fonts, or graphics rendering, so your browser fingerprint is unchanged. That is why a VPN alone does not defeat fingerprint-based tracking.
The screen is the whole display; the viewport is the part of it your page occupies, after browser chrome, scrollbars and zoom. On a phone the difference also includes the address bar, which changes size as you scroll.
No. It is read and displayed locally, and disappears when you close the tab.
Nothing you enter here leaves your browser
Browser Info - What Your Browser Reveals does its work in JavaScript running on your own device. The page loads once, and after that there is no upload step and no server involved — which matters here because diagnostic output tends to describe your own network and machine.
You can verify this rather than taking our word for it: load the page, disconnect from the internet, and the tool keeps working. Our privacy policy sets out what is and is not collected, and this guide explains why the distinction matters.