User-Agent Switcher is a Chrome add-on developed by capitalism99. It is a free tool that allows users to switch their User-Agent strings to mimic, spoof, or fake other browsers or bots.

With User-Agent Switcher, you can change your user agent to spoof other devices and browsers. This enables you to access Internet Explorer-only websites by pretending to be using Internet Explorer. You can also blend in as an iPhone or test how websites render when they think you're Google's search spider.

The add-on is both simple and powerful. It adds a toolbar button that allows you to easily toggle between different commonly used user agent strings. Additionally, you have the option to enter your own custom user agent string.

By overriding Chrome's default user agent, User-Agent Switcher tricks websites into believing that you're using a different browser. This can be useful for testing website compatibility or accessing content that is restricted to specific browsers.

A user agent is a small text description of your device that is sent with every web request. Websites can detect the browser you're using and serve different content based on that information. This is why iPhone and Android users often see special mobile websites when they browse the web.