XML-TEI

TextWrangler is a general purpose text editor developed for Mac OS X. TextWrangler is suitable for "light-duty composition, data-file editing (where the data files consist of plain [unstyled] text), and manipulation of text-oriented data".

oXygen XML Editor is a cross-platform textual editing and markup tool. oXygen XML Editor is the "best XML editor available" due to its incredible breadth: it supports all XML schema languages and accommodates "a large number of users ranging from beginners to XML experts". The oXygen XML Editor is designed to work with all XML-based technologies, ranging fro XML databases to web services. The oXygen XML Editor user-friendly interface is designed with special consideration for content authors making this tool the complete editing solution for XML projects.