User Agent Parser

User Agent Syntax

The syntax of a user agent string is:

User-Agent: <product> / <product-version> <comment>

The common format for a browser user agent string is:

User-Agent: Mozilla/5.0 (<system-information>) <platform> (<platform-details>) <extensions>

For example, the user agent string for Firefox is:

Mozilla/5.0 (platform; rv:geckoversion) Gecko/geckotrail Firefox/firefoxversion

Mozilla/5.0 is the token for the browser

platform is the platform that the browser is running on (e.g. Windows, Max, Linux, etc.)

rv:geckoversion is the version of the Gecko browser engine.

Gecko/geckotrail means the browser is based on the Gecko browser engine.

Firefox/firefoxversion is the Firefox version number.