Chrome Mask is a Firefox extension designed for web developers and testers, providing a seamless way to spoof the user agent as Chrome on specific websites. Unlike generic user agent spoofing extensions, Chrome Mask allows users to selectively apply the Chrome mask, making it a more tailored solution for testing website compatibility. The extension automatically updates to the latest Chrome version every 24 hours by querying an API, ensuring that users are always mimicking the most current browser version.

Additionally, Chrome Mask simplifies the process by automatically selecting the appropriate operating system for the spoofed user agent. It enhances its functionality by shimming essential JavaScript attributes, such as navigator.vendor and the global chrome object, which helps in passing common browser compatibility checks. This makes it a valuable tool for developers who need to test their applications across different browser environments.