Mozilla Composer is the former free and open-source HTML editor and web authoring module of the Mozilla Application Suite (the predecessor to SeaMonkey). It was used to create and to edit web pages, e-mail, and text documents, and available for Windows, macOS and Linux. Composer was a graphical WYSIWYG HTML editor to view, write and edit HTML source code.[1]
In September 2008 Daniel Glazman announced a new WYSIWYG HTML editor, BlueGriffon, written from scratch and based on Mozilla Gecko and XULRunner.
SeaMonkey, the community-driven successor to Mozilla Suite, includes an HTML editor named Composer that is developed from the Mozilla Composer code contained in the original Mozilla Suite.[1]