Quick Answer: A user agent is a text string your browser sends to every website identifying your browser, OS, and device. See yours instantly at What's My User Agent. Example:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36
What Is It?
Every time your browser loads a webpage, it sends a User-Agent header that tells the website:
- Which browser you use (Chrome, Firefox, Safari, Edge)
- Your browser version
- Your operating system (Windows, macOS, Linux, Android, iOS)
- Your device type (desktop, mobile, tablet)
Websites use this to serve the right version of their page — mobile layout for phones, desktop for computers.
Find Your User Agent
Instant Check
Visit What's My User Agent — shows your full string parsed into browser, version, OS, and device.
In Browser Console
Press F12 → Console tab → type:
navigator.userAgentCommand Line
curl -s httpbin.org/user-agentWhat Does It Look Like?
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36Breaking it down:
| Part | Meaning |
|---|---|
Mozilla/5.0 |
Historical compatibility token (every browser sends this) |
Windows NT 10.0; Win64; x64 |
Operating system: Windows 10/11, 64-bit |
AppleWebKit/537.36 |
Rendering engine |
Chrome/124.0.0.0 |
Browser and version |
Safari/537.36 |
Compatibility token (Chrome pretends to be Safari for legacy reasons) |
Common User Agents
| Browser | Example |
|---|---|
| Chrome (Windows) | Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 Chrome/124.0 |
| Chrome (Mac) | Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 Chrome/124.0 |
| Firefox | Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:125.0) Gecko/20100101 Firefox/125.0 |
| Safari (Mac) | Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 Version/17.4 |
| Safari (iPhone) | Mozilla/5.0 (iPhone; CPU iPhone OS 17_4 like Mac OS X) AppleWebKit/605.1.15 Mobile |
| Edge | Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 Edg/124.0 |
Privacy Concerns
Your user agent reveals:
- Operating system and version
- Browser and exact version
- Device type (mobile/desktop)
- CPU architecture (x64, ARM)
Combined with other data (IP, screen size, fonts, plugins), this creates a browser fingerprint that can track you across websites — even without cookies.
User Agent Reduction
Modern browsers are reducing the information in user agents for privacy. Chrome has been gradually freezing parts of the string — older minor versions are replaced with 0 to reduce fingerprinting surface.
How to Change Your User Agent
Chrome DevTools
- Press F12 → click the three dots menu → More tools → Network conditions
- Uncheck Use browser default under User agent
- Enter a custom user agent string
Firefox
- Type
about:configin the address bar - Search for
general.useragent.override - Type the name in the search bar, click + to create it (String type) and enter your custom user agent
Browser Extensions
Install a "User-Agent Switcher" extension to easily switch between different user agents.
Related Tools
- What's My User Agent — see your parsed user agent
- Browser Info — full browser and device details
- What's My IP — check your IP and location
- VPN Leak Test — check browser privacy