FireTeX, web based LaTeX editor complete, is a powerful, intuitive and stocked with useful functions for exporting the results in three useful formats. An editor with LaTeX compiler, highlight code, advanced search / replace and filesystem API HTML5.
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Android app available on Play Store > https://play.google.com/store/apps/details?id=com.ulmdesign.ulmtex
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Update 30.06.2017
Windows 7 and later and macOS 10.9 and later are supported.
== Browser Extensions ==
Add-on...
A bundle of lisp extensions, largely original, for GNU Emacs with the goal to obtain a more user friendly and powerful interface. The new features include contextual tool bars, new TeX interface, very complete menus, and a well structured IDE.
DragMath is a drag and drop equation editor in the form of a Java applet. Once an expression is created the user can convert it into a variety of different linear syntax for mathematics, including MathML, LaTeX, Maple, Maxima or any user defined style.
PLEASE NOTE: active code development has moved to GitHub.
https://github.com/maths/dragmath