Webオーサリングツール
Mozilla Composer is the free and open-source HTML editor and web authoring module of the Mozilla Application Suite (the predecessor to SeaMonkey). It is used to create and to edit web pages, e-mail, and text documents easily. It is compatible with Windows, macOS and Linux. Composer is a graphical WYSIWYG HTML editor. One also can view, write and edit HTML source code with Composer.