JMathEdit is described as 'equation editor that helps editing complex mathematical expressions with ease' and is a LaTeX Editor in the education & reference category. There are more than 10 alternatives to JMathEdit for a variety of platforms, including Windows, Mac, Linux, Online / Web-based and Self-Hosted solutions. The best alternative is LibreOffice - Math, which is both free and Open Source. Other great apps like JMathEdit are MathType, TexMaths, EqualX and Apache OpenOffice Math.
Math is the LibreOffice suite's formula editor, that can be invoked in your text documents, spreadsheets, presentations and drawings, to enable you to insert perfectly-formatted mathematical and scientific formulas.
MathType is a powerful interactive equation editor for Windows and Macintosh that lets you create mathematical notation for word processing, web pages, desktop publishing, presentations, elearning, and for TeX, LaTeX, and MathML documents.
TexMaths is an addon designed to provide LaTeX support into LibreOffice. LaTeX equations can be inserted as images (SVG or PNG formats) and the LaTeX code is saved into the image attribute for further editing.
Math, part of the Apache OpenOffice suite, is a tool for creating and editing mathematical equations, similar to Microsoft Equation Editor (included in Microsoft Office). The created equations can then be embedded inside other OpenOffice.
iMathEQ is a mathematics equation or formula editor. It is a WYSIWYG online equation/formula editor allowing users to input, edit, print math equation or expressions. Provide interface for easy integration with web site or mobile app.