What is User-Agent String?
An HTTP header that identifies the software making a web request, such as a browser or crawler.
The User-Agent string is an HTTP request header sent with every web request. It typically identifies the browser, operating system, and rendering engine. For crawlers, it identifies the bot name and operator, allowing site owners to distinguish between different types of automated visitors.
Example browser UA: "Mozilla/5.0 (Windows NT 10.0; Win64; x64) Chrome/120.0.0.0 Safari/537.36" Example bot UA: "Mozilla/5.0 (compatible; GPTBot/1.2; +https://openai.com/gptbot)"
User-agent strings are the primary mechanism for identifying cooperative crawlers. robots.txt rules target specific user-agent values. However, UA strings can be easily spoofed, which is why behavioral detection (like Switch's fingerprinting) is important for reliable bot identification.
How Switch Helps
Switch uses user-agent strings as one of many signals for agent detection, combined with behavioral analysis and fingerprinting for higher accuracy.
Get Started Free