A schema-driven XML editor for the web
version 3.3.0
XML data demo XML document demo

Xonomy is a web-based, schema-driven XML editor, written entirely in JavaScript and embeddable in any web page. Xonomy emulates the look and feel of a text editor with syntax highlighting, code folding and autocompletion. It is, however, not a text editor: you edit your XML documents by clicking on nodes, selecting options from context menus, selecting attribute values from picklists, dragging and dropping elements around, and so on.

You can customize Xonomy by giving it a document specification. A document specification is similar to a schema: it determines what actions the user can perform on each element, which attributes or child elements the user can create, where attribute values come from, and so on. This gives you a mechanism for constraining the structure of your XML documents which is roughly equivalent to a Document Type Definition (DTD). You can constrain your document further by attaching your own validation functions in JavaScript.

Xonomy can handle both data-centric XML, which it displays in a tree structure, and document-centric XML, which is displayed as running text with inline XML markup. Xonomy is able to handle mixed content (elements which contain a mixture of text and elements) and has features for annotating text with inline XML. Xonomy can work with documents that use namespaces.

A ZIP file containing xonomy.js, xonomy.css and some supporting files.
MIT License
50 pages of instructions on how to integrate Xonomy into your applications (PDF).