Editing tools and conversion tools from legacy formats can make all the difference when one decides to move over to a markup format for mathematical documents. The JEM portal devotes an entire section of the wiki to editing sofwtare, http://www.jem-thematic.net/en/node/232, and also a few software description pages, http://www.jem-thematic.net/view/software. Here below we just make a selection that concentrates on tools specifically geared towards markup.

The MathDox formula editor is a web-based editor for mathematical formulas that produces an OpenMath representation of the formula and can be easily integrated into existing HTML pages since it is written in javascript. It is intended for usage in interactive pages where users are required to answer. See more on JEM pages and on distribution page.

Another OpenMath/MathML editor intended for web applications, and developed as a java applet, is available from Maths for More, it is called WIRIS OpenMath tools. For OpenMath advanced users, the applet can be configured to create new symbols, associate one or several graphical representations to it and, finally, use the new symbols through a toolbar in the editor. WIRIS Editor can be tested at http://www.wiris.com/demo/omeditor.

The java editor jEditOQMath is also available for supporting the creation, editing and to some extent, the management of collections of OMDoc documents for use in the ActiveMath learning environment by XML-editing, validation, and template-supported creation of OQMath documents. Built-in scripts simplify the publication on the ActiveMath server and the input of mathematical formulae by on-the-fly by using the QMath converter from a common and easy to read syntax to OpenMath. Entering mathematics is as simple as writing expressions such as $3a+5b$ or $Hn = set(x | x ∈ Rn ∧ π(n,x) > 0)$ that are converted during the build-scripts-run to OpenMath. See the developer snapshot from jEditOQMath's home page.

LaTeXML would be the choice for those authors already familiar with LaTeX, the widely used typesetting system for mathematics. The goals of LaTeXML are a faithful emulation of TeX's behaviou, extensibility by packages, preservation of both semantic and presentation cues, abstract LaTeX-like, extensible, document type and possibility to support the semantics of mathematical content by good Presentation MathML, and eventually Content MathML and OpenMath. See more on the JEM page and in the presentation Why TeX and LaTeXML?.
Similarly, sTeX: Semantically Enhanced TeX provides specialized macro packages, to authors wishing to add semantic information to the document without changing the visual appearance. The information in the semantically pre-loaded sTeX source allows automatic conversion to content-oriented, XML-based formats, like CNX, C-MathML, OMDoc, Dublin-Core, and PhysML via the LaTeXML Transformer, de facto creating an XML production workflow. Using this process on own legacy documents will involve to some extent the creation of new “LaTeXML bindings”, i.e. directives to the LaTeXML emitter that specify the target representation in XML. See more on the JEM page and the case study in which the learning material was generated using sTeX.