AVIM is an extension for Firefox, Thunderbird, Komodo, and similar applications that functions as an input method editor for Vietnamese, allowing you to insert diacritical marks easily everywhere you can type. This extension, along with a basic Chrome extension of the same name, are based on the avim.js script by Hiếu Đặng. Read more about AVIM for Firefox. Important: Firefox 57 is incompatible with AVIM due to the new WebExtensions feature that is replacing traditional extensions. AVIM cannot be updated to work in Firefox 57 until AVIM’s most basic functionality is possible in WebExtensions. Please subscribe to this issue and vote for any Bugzilla bug reports mentioned there. Thank you for your understanding.