Gecko is a browser engine developed by Mozilla. It is used in the Firefox browser, the Thunderbird email client, and many other projects. Gecko is designed to support open Internet standards, and is used by different applications to display web pages and, in some cases, an application’s user interface itself. Gecko offers a rich programming API that makes it suitable for a wide variety of roles in Internet-enabled applications, such as web browsers, content presentation, and client/server. Gecko is written in C++ and JavaScript, and, since 2016, additionally in Rust. It is free and open-source software subject to the terms of the Mozilla Public License version 2. Mozilla officially supports its use on Android, Linux, macOS, and Windows. Developer(s): Mozilla Foundation, Mozilla Corporation, Adobe Systems, and other contributors Written in: C++, JavaScript, Rust Type: Browser engine License:MPL 2.0