Latest Windows User Agent Strings: Chrome, Edge & Firefox on Windows 10/11

Latest Windows User Agent Strings (Copy-Ready)

As of July 17, 2026, these are the current user agent strings on Windows 10 and Windows 11 — both OS versions send the exact same strings. Google Chrome 150 (stable since June 30, 2026):

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/150.0.0.0 Safari/537.36

Microsoft Edge 150 — Chrome’s string plus the Edg/ token:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/150.0.0.0 Safari/537.36 Edg/150.0.0.0

Mozilla Firefox 152 — the Gecko engine format:

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:152.0) Gecko/20100101 Firefox/152.0

Chromium browsers froze the minor version digits at 0.0.0 (Chrome 101, April 2022) and the platform token at Windows NT 10.0; Win64; x64 (Chrome 107, October 2022) as part of the User-Agent Reduction program — so Edge 150’s real build is 150.0.4078.x, but its UA still says Edg/150.0.0.0. Per-browser details live on our Chrome, Edge, and Firefox user agent pages.

Chrome User Agent Strings by Version (139–150) with Release Dates

Because only the major version changes, you can reconstruct any recent Chrome-on-Windows user agent from its release. All dates are from the official Chromium release schedule — including Chrome 139 (August 5, 2025) and Chrome 140 (September 2, 2025):

Chrome 151 is scheduled for July 28, 2026. See which build you’re on with our Chrome version checker, or check the latest Windows version underneath the browser.

The Windows 11 Detection Dilemma: User-Agent Client Hints

Notice that every string above says Windows NT 10.0 — even on Windows 11. The token is deliberately frozen: bumping it would break decades of legacy browser-sniffing code, and Chromium’s UA Reduction stripped OS details to limit fingerprinting. Microsoft is explicit that “User-Agent strings won’t be updated to differentiate between Windows 11 and Windows 10.” The sanctioned replacement is User-Agent Client Hints (UA-CH).

Chromium browsers send three low-entropy hints with every request — Sec-CH-UA (browser brands), Sec-CH-UA-Mobile, and Sec-CH-UA-Platform (“Windows” for both OSes). To tell Windows 11 apart, your server must opt in to the high-entropy Sec-CH-UA-Platform-Version header via Accept-CH (add Critical-CH to get it on the very first request):

Accept-CH: Sec-CH-UA-Platform, Sec-CH-UA-Platform-Version
Critical-CH: Sec-CH-UA-Platform-Version

The first number of the returned platform version tells you the OS: 13 or higher means Windows 11, 1–12 means Windows 10, and 0 means an older Windows (the values derive from Windows’ UniversalApiContract, which is why Windows 11 is 13, not 11). In JavaScript, Microsoft’s documented detection looks like this:

navigator.userAgentData.getHighEntropyValues(["platformVersion"])
 .then(ua => {
   if (navigator.userAgentData.platform === "Windows") {
     const majorPlatformVersion = parseInt(ua.platformVersion.split('.')[0]);
     if (majorPlatformVersion >= 13) {
       console.log("Windows 11 or later");
     }
     else if (majorPlatformVersion > 0) {
       console.log("Windows 10");
     }
     else {
       console.log("Before Windows 10");
     }
   }
   else {
     console.log("Not running on Windows");
   }
 });

One big caveat: UA-CH is Chromium-only (Chrome 89+, Edge, Opera). Firefox and Safari don’t implement it — navigator.userAgentData is undefined there and no Sec-CH-UA headers are sent — so feature-detect first and accept that in those browsers Windows 10 and 11 are indistinguishable. Since detection differs per engine, the reliable way to verify OS-specific behavior is to test on real Windows browsers rather than trust the string.

What Is an “Agent Browser” vs. a Browser “User Agent”?

The two terms look similar but mean very different things. A browser’s user agent is metadata: the HTTP header string identifying which browser and OS are making a request — everything this page has covered so far. An agent browser is software: automation tooling built so AI agents can drive a real browser themselves — navigating, clicking, and filling forms programmatically.

The best-known example is Vercel’s open-source agent-browser CLI, launched in January 2026 — a Rust-based tool that drives Chrome over the DevTools Protocol. An AI agent runs agent-browser open, gets a compact accessibility snapshot of the page with element references like @e1, and then acts on them (agent-browser click @e2), which Vercel says uses a fraction of the context a raw DOM dump would. It installs with npm install -g agent-browser and plugs into agents like Claude Code and Cursor, alongside a broader 2026 category of agentic browsing — from Playwright MCP to consumer AI browsers. Ironically, agent browsers still send a normal user agent string when they browse — the two concepts meet in your server logs.

Windows User Agent Format Explained

Taking Chrome’s string apart token by token:

• Mozilla/5.0: A legacy prefix every modern browser sends — a relic of 1990s Netscape compatibility that now carries no information.
• (Windows NT 10.0; Win64; x64): The frozen platform token — Windows 10 and 11, 64-bit. Older strings you’ll still see in logs: Windows NT 6.1 (Windows 7, e.g. from Firefox ESR 115) and Windows NT 6.3 (Windows 8.1).
• AppleWebKit/537.36 (KHTML, like Gecko): Frozen engine tokens. WebKit descends from KDE’s KHTML, and “like Gecko” was added so sites serving Gecko-optimized content would treat WebKit browsers equally — pure compatibility theater at this point.
• Chrome/150.0.0.0: The browser and its major version — minor digits frozen at 0.0.0 since Chrome 101.
• Safari/537.36: Another compatibility token, claiming Safari compatibility for legacy sniffers. Edge appends Edg/150.0.0.0 after it; Opera appends OPR/.

How to Check Your Windows User Agent

If you're curious about your Windows user agent, here’s how you can find it:

• Open your preferred browser (Chrome, Firefox, Edge, etc.)
• Press F12 to open the Developer Tools.
• Go to the Console tab and type navigator.userAgent — or find the User-Agent request header on any request in the Network tab.
• Or skip DevTools entirely: our free What Is My User Agent tool shows your string instantly, and the user agent parser decodes any string into its tokens.

Why the Windows User Agent Matters

Here are a few reasons why understanding and managing your Windows user agent is important:

• Browser Compatibility: Ensure your website or web application functions correctly across different browsers and devices — and remember the frozen tokens mean the string alone can’t tell you the real OS build.
• Performance Optimization: Some web servers or services may deliver different resources based on the user agent, which can improve loading times and performance.
• Tracking & Analytics: The user agent helps websites track visitor demographics, device types, and operating systems — though since UA Reduction, analytics that need OS detail must adopt Client Hints.

What is my User Agent?

Frequently Asked Questions About Windows User Agents

What is an agent browser?

An agent browser is automation tooling that lets AI agents drive a real web browser programmatically — navigating pages, clicking elements, and filling forms on the agent's behalf. The best-known example is Vercel's open-source agent-browser CLI (launched January 2026), which gives AI coding agents compact page snapshots with element references they can act on. This is different from a browser's 'user agent', which is just the HTTP header string identifying the browser to websites.

What is the user agent string of Chrome?

On Windows, the current Chrome user agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/150.0.0.0 Safari/537.36. Since Chrome 101, the minor.build.patch digits are frozen at 0.0.0 — only the major version (150) changes with each release. The full build number is available only through User-Agent Client Hints.

What does KHTML, like Gecko mean?

It's a historical compatibility token. WebKit — the engine behind Safari, and the ancestor of Chromium's Blink — was originally forked from KHTML, the KDE project's engine. 'like Gecko' was added so websites that served content based on Mozilla's Gecko engine would treat WebKit browsers the same way. Every WebKit/Blink browser still sends 'AppleWebKit/537.36 (KHTML, like Gecko)' purely so legacy browser-sniffing code keeps working.

What is Mozilla 5.0 in user agent?

Mozilla/5.0 is a legacy prefix that every modern browser sends, regardless of vendor. In the 1990s, servers gave the best content to Netscape ('Mozilla'), so competing browsers began claiming the token for compatibility — and it stuck. Today it carries no real information; it simply marks the string as a Mozilla-compatible user agent.