← Back to headers
HTTP Header
User-Agent
RequestIdentifies the client software making the request.
HTTP header reference, syntax, examples, and developer usage.
What is the User-Agent header?
The User-Agent HTTP header is used to transmit metadata between a client and server as part of HTTP requests or responses.
HTTP headers define how content should be interpreted, cached, authenticated, secured, or processed by browsers and APIs.
Direction
This is a request header sent by the client to the server.
Syntax
User-Agent: <client info>
Example
User-Agent: Mozilla/5.0
Common use cases
- Logging client types
- Analytics
- Conditional server-side behavior
Common mistakes
- Using the header in the wrong request or response context
- Sending invalid header values
- Incorrect header syntax
- Assuming the header automatically changes server behaviour