XRay is a free XML editing enviroment. Now in its second major release, XRay provides support for XML Schema (XSD) and an integrated online XML tutorial system.
webDevStudio is an online integrated development environment (IDE) based on PHP technology. Any software developer would be able to design computer science projects with or without of greater or smaller complexity, using only a Web navigator and without worrying about file and project management (creation, modification, compilation, etc.). Tool would be completely in charge of the projects and registered users. From server machine, it would be provided to developers a set of operations integrated in a powerful graphic interface without having installed in client machine any development component (compiler, code editor, etc).
webDevStudio integrates a simple resource manager whose basic undertaken will consist of maintaining always consistency between server and client machine. User management controls users which are registered and who would have access granted to the tool. Project management controls projects created by users and allows to build them and make backup copies. File management controls files which owns to each project, and they can be downloaded, modified and compiled at any moment.
Liquid XML Studio is a FREE XML Schema Editor, and much more.
Simple enough for new users to pick up quickly and comprehensive enough for experienced users deal with the advanced features of the XSD standard.
KG: Free, but not open source. For the quick schema edit...
CodePress is web-based source code editor with syntax highlighting written in JavaScript that colors text in real time while it's being typed in the browser