Dev UtilitiesLesson 142Free preview
User Agent Parser
This lesson is part of Web Developer Tools · All levels
Summary
The User Agent Parser reads the user-agent string that the browser sends on each HTTP request, then breaks it down into browser names, versions, rendering machines, operating systems, and device types. This information is useful for adjusting the look, reading visitor statistics, or diagnosing compatibility issues. Keep in mind that these strings are sent by the client so they can be counterfeited and should not be used as a security base.
Key points
- The User-Agent Header is part of the HTTP request and contains the identity of the client
- Parser breaks down parts such as browser, version, engine, OS, and device type
- Useful for analytics, compatibility debugging, and responsive display testing
- User-Agent values can be changed by the client, so don't use them for authentication.
- Modern browsers provide Client Hints as a more structured alternative
Full lesson
Code examples and quizzes
Full lessons, code examples, and quizzes are available to subscribers. 5 questions.