Your Browser Identity
This is the unique signature your browser sends to every website you visit.
Understanding the User Agent String in 2026
Every time you browse the web, your browser introduces itself using a "User Agent" string. Learn why this technical handshake is vital for the modern web.
Cross-Device Testing
Developers use User Agents to serve specific content, ensuring that a site looks perfect on an iPhone, Android, or Windows PC.
Security & Privacy
Identify suspicious login attempts by checking if the User Agent matches the known devices associated with your accounts.
Bot Detection
Web servers distinguish between human visitors and search engine crawlers (like Googlebot) by analyzing the User Agent.
What is a User Agent (UA)?
A User Agent is a line of text that acts as a digital fingerprint. It tells the web server which software (Chrome, Firefox, Safari), which operating system (Windows 11, iOS 19, macOS), and which rendering engine (WebKit, Blink) you are using.
Why Does Every UA String Start with "Mozilla/5.0"?
This is one of the internet's oldest quirks. In the early days, websites checked for "Mozilla" to determine if a browser supported frames. To ensure compatibility, every modern browser—including Chrome and Edge—still includes "Mozilla/5.0" at the beginning of its signature so that websites don't block them or serve a "fallback" version.
User Agent Client Hints (UA-CH): The Future
In 2026, privacy-focused browsers are moving away from the full UA string toward "Client Hints." This is a more secure way for browsers to provide only the necessary information to a website, reducing "browser fingerprinting" which can be used to track users without their consent. Our **Dynamic UA Finder** detects both the traditional string and the modern platform hints.