Mozilla Firefox Quantum is one of the fastest and stable browsers that directly compete with Google Chrome and Microsoft Edge.
Firefox is very popular in the Linux ecosystem as it has features like tracking protection to prevent unwanted domain requests. Thus, it loads the page relatively faster, and it is more privacy secured than others.
It does not use the Chrome-based source code; Mozilla has its HTML rendering engine. There is no extension support, but there is Add-ons support similar to Chrome and Edge extensions.
Firefox has a well-designed, clean, and simple UI, which remarkably eases navigating and using Homepage icons. All the essential features like bookmarks and favorite URL, password management, form and payment auto fill, etc., are available. You can add a guest account for quick sign-in, and of course, you can sync data via logging into the free Mozilla Firefox account.
Firefox supports various web applications and also has its web application, like the built-in task manager to manage web pages on tabs. It is considered a developer-friendly browser that supports every type of add-ons (aka extensions) to enhance development.
Majorly build for and supported by the Linux OS community, the Firefox Quantum browser is also available for Windows, macOS, Android, and iOS.