User Agent
Introduction
Every time you browse the internet, your device sends a digital “ID card” to websites—this is called the User Agent (UA). It tells servers what browser, operating system, and device you’re using so they can optimize content delivery. User Agents also play a crucial role in privacy, security, and multi-account management. Websites employ them for fingerprinting, tracking, and detecting suspicious activity. For professionals managing multiple accounts—such as marketers, e-commerce sellers, or affiliate managers—controlling User Agents is essential to avoid bans and maintain anonymity.
What is a User Agent?
A User Agent is a string of text that browsers send to web servers, identifying the software and hardware making the request. A typical example looks like:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36
This string reveals:
- Browser: Chrome 120.0.0.0
- Operating System: Windows 10 (64-bit)
- Rendering Engine: AppleWebKit/537.36
Websites use this data to serve device-optimized layouts, block outdated browsers for security, and track users via browser fingerprinting.
Key Components of a User Agent String
Now that we know what a UA string does, let’s break down its main parts:
- Browser Name & Version (e.g., Chrome/120.0.0.0)
- Operating System (e.g., Windows NT 10.0)
- Device Type (e.g., Mobile, Tablet, Desktop)
- Rendering Engine (e.g., AppleWebKit/537.36)
- Compatibility Flags (e.g., “like Gecko”)
For example, an Android phone’s UA might read:
Mozilla/5.0 (Linux; Android 14; SM-G998B) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Mobile Safari/537.36
Here, SM-G998B identifies a real Samsung Galaxy S21 model, making the UA appear more legitimate than spoofed strings.
Why User Agents Matter
A UA string is more than a header—it’s a cornerstone of how websites interact with you.
- Website Compatibility: Deliver mobile or desktop layouts and enable specific features.
- Privacy Risks: Contribute to browser fingerprinting even with cookies disabled.
- Multi-Account Management: Platforms flag shared UA strings; unique UAs help avoid detection.
- Security & Anti-Bot Measures: Financial sites block emulator-generated strings.
Given these stakes, many turn to UA spoofing—but it has serious drawbacks.
User Agent Spoofing & Its Limitations
Users often change their UA to access restricted content, test across devices, or hide their real browser/OS. Common methods include DevTools, extensions, and antidetect browsers. However:
- Inconsistencies: A Windows UA on a Mac triggers alerts.
- Fingerprinting Gaps: WebGL and Canvas checks expose fakes.
- App Blocking: TikTok and Instagram detect non-native UAs.
Why GeeLark Excels
Rather than faking UA strings, GeeLark simulates real Android devices in the cloud. Each cloud phone has a genuine UA tied to actual hardware. You also get:
- Proxy Integration: Route traffic through geolocated IPs.
- API Control: Automate UA rotation and device provisioning.
- App Compatibility: Run TikTok, Facebook, and more without detection.
Technical Demo: Rotating UA via API
curl -X POST https://api.geelark.com/v1/devices/{device_id}/user-agent
-H 'Authorization: Bearer YOUR_API_TOKEN'
-H 'Content-Type: application/json'
-d '{"rotate": true}'
Sample JSON Response:
{
"device_id": "12345",
"user_agent": "Mozilla/5.0 (Linux; Android 13; Pixel 6) AppleWebKit/537.36 Chrome/125.0.0.0 Mobile Safari/537.36"
}
Managing User Agents for Multi-Account Operations
Professionals using multiple accounts—e-commerce, affiliate marketing, ad management—need unique, realistic UAs. With GeeLark:
- Deploy cloud phones with distinct device models.
- Assign each instance its own proxy.
- Schedule UA rotations to mimic natural user behavior.
This approach ensures seamless scaling without triggering anti-fraud systems.
Conclusion & Next Steps
Traditional spoofing and emulators no longer suffice against advanced detection. GeeLark’s antidetect cloud phones deliver:
- Real Android Devices – No emulator fingerprints.
- Unique UA Strings – Matched to genuine hardware.
- Proxy Support – Dedicated, geolocated IPs.
- App Compatibility – Run all major social and e-commerce apps undetected.
Ready to transform your UA management?
Get started with a 7-day free trial of Antidetect Phone or schedule a demo to see cloud phones in action.
People Also Ask
What is an example of a user agent?
Here’s a common User-Agent string sent by Chrome on Windows 10:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36
Where do I find my user agent?
You can view your User-Agent in several ways:
• In your browser’s Developer Tools: press F12 (or Ctrl + Shift + I), go to the Network tab, reload the page, click any request, and inspect the “User-Agent” header.
• In the JavaScript console: type navigator.userAgent and press Enter.
• In Chrome: visit chrome://version and look for “User Agent.”
• In Firefox: go to about:support and find the “User Agent” entry.
• Use an online checker: search “what is my user agent” or visit a site like whatsmyua.info.
What is user agent spoofing?
User agent spoofing is the practice of altering the User-Agent header that browsers send to web servers. By modifying or masking this string, you can make a server think you’re using a different browser, operating system, or device. This is used for privacy, bypassing restrictions, or testing site compatibility.
What are suspicious user agents?
Suspicious User-Agent strings often deviate from normal browser patterns or identify known bot tools. Examples include:
• “curl/7.68.0” or “Wget/1.20.3”
• “python-requests/2.25.1” or “Java/1.8.0_241”
• Overly generic values like “Mozilla/5.0” with no platform details
• Random or malformed strings (lots of symbols or uneven syntax)
• Mismatches between claimed device and other headers
These signs often indicate automated scripts, scrapers, or malicious bots rather than genuine human-driven browsers.