XML Editor is a markup language editor with added functionality to facilitate the editing of XML. This can be done using a plain text editor, with all the code visible, but XML editors have added facilities like tag completion and menus and buttons for tasks that are common in XML editing, based on data supplied with document type definition (DTD) or the XML tree.

XML Editor goes beyond the syntax highlighting offered by many plaintext editors and generic source code editors, verifying the XML source based on an XML Schema or XML DTD, and some can do it as the document is being edited in real time.