XML Notepad 2006, written in C# 2.0, is a free and open source (you can check the source at installed directory) simple XML editor for us which quick and dirty .
Notepad? sounds like it, while strong enough, many handy features include:
- Tree View synchronized with Node Text View for quick editing of node names and values.
- Incremental search (Ctrl+I) in both tree and text views, so as you type it navigates to matching nodes.
- Cut/copy/paste with full namespace support.
- Drag/drop support for easy manipulation of the tree, even across different instances of XML Notepad and from the file system.
- Infinite undo/redo for all edit operations.
- In place popup multi-line editing of large text node values.
- Configurable fonts and colors via the options dialog.
- Full find/replace dialog with support for regex and XPath.
- Good performance on large XML documents, loading a 3mb document in about one second.
- Instant XML schema validation while you edit with errors and warnings shown in the task list window.
- Intellisense based on expected elements and attributes and enumerated simple type values.
- Support for custom editors for date, dateTime and time datatypes and other types like color.
- Handy nudge tool bar buttons for quick movement of nodes up and down the tree.
- Inplace HTML viewer for processing xml-stylesheet processing instructions.
- Built-in XML Diff tool.
Go to download link.