How to use it

Open the page. Your user agent appears in the box, with the decoded browser and system in the line above it.
Press Copy user agent to paste the exact string into a bug report or a support chat.
Check the Client Hints row for the precise version and platform your browser gives out on request.
Resized the window or changed a setting? Press Refresh.

How to read a user agent string

Browser strings follow an old pattern: Mozilla/5.0 (system information) platform (platform details) extensions. Almost every browser starts with Mozilla/5.0 for historical reasons, so the useful parts are in the brackets and the last tokens. Here is a current Chrome string on Windows, taken from MDN's reference:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/143.0.0.0 Safari/537.36

The same string, part by part
Part	What it means
`Mozilla/5.0`	Compatibility token. It tells you nothing
`Windows NT 10.0; Win64; x64`	64-bit Windows. Windows 10 and 11 both send 10.0
`AppleWebKit/537.36 (KHTML, like Gecko)`	Compatibility tokens that Chromium-based browsers add. With Chrome in the string, this page reports the Blink engine
`Chrome/143.0.0.0`	The major version is real; the minor numbers are always zeros
`Safari/537.36`	Another compatibility token, not a sign of Safari

Edge adds Edg/, Opera adds OPR/, and Firefox ends with Gecko/20100101 Firefox/ plus its version. The decoder checks those tokens before falling back to Chrome.

Why the version and system look out of date

Browsers now freeze parts of the string to make tracking harder. Chrome on Android always reports Android 10; K, whatever the real version and phone model. Chromium browsers on a Mac, and Safari, report Mac OS X 10_15_7. Microsoft says the Windows string won't be updated to tell Windows 11 from 10, which is why this page shows Windows 10 or 11.

On iPhone and iPad, Chrome, Firefox and Edge are built on Apple's WebKit engine, so their strings look like Safari's apart from a token such as CriOS/.

Client Hints: the newer way

Chromium-based browsers such as Chrome, Edge and Opera also support User-Agent Client Hints. Every request carries the low-entropy hints: the brand and major version (Sec-CH-UA), whether the device is mobile, and the platform name. Details such as the full version, platform version, CPU architecture and model are high-entropy hints that a site has to ask for. This page asks with getHighEntropyValues() and shows the answer in the Client Hints row. Firefox doesn't support them, so it shows Not supported by this browser.

To tell Windows 11 from Windows 10, look at the platform version in that row. Microsoft's guidance: a first number of 13 or higher means Windows 11; 1 to 10 means Windows 10.

What any website reads without asking

The table under What any website can read without asking lists values a page's script can read without a permission prompt: your languages, time zone, screen and window size, CPU threads, device memory, touch support, and your Do Not Track, Global Privacy Control, colour scheme and reduced-motion settings. None of them is secret alone. Together with your IP address they make a browser easier to recognise, which is called fingerprinting.

The decoding runs in your browser. The one request to this site fetches the Accept-Language header row: the language list your browser actually sent with the page.

Questions

Why does a newer Mac show macOS 10.15.7?: That number is frozen in the user agent of Safari and Chromium browsers. The page labels it 10.15.7 or later. Client Hints, where supported, carry the real version.
Why does every browser say Mozilla?: For historical compatibility. MDN notes that almost every browser today sends the Mozilla/5.0 token, so it can't be used to tell browsers apart.
What does 'Available (details on request)' mean?: Your browser supports Client Hints but didn't hand over the detailed values when this page asked for them, so only the low-entropy hints are known.
Is my user agent personal data?: On its own it's shared by everyone with the same browser version and system. It becomes identifying when combined with the other values on this page and your IP address.
Does this page keep my user agent?: No. It's shown only to you and isn't stored. See how our tools work.

Results come from public DNS, registry and certificate data and from checks run from Cloudflare's network at the moment you ask. They can differ from what another network sees. How our tools work · Terms of use.

What is my user agent?