jedit

jEdit is a mature programmer's text editor with hundreds (counting the time developing plugins) of person-years of development behind it.

Some of jEdit's features include:

• Written in Java, so it runs on Mac OS X, OS/2, Unix, VMS and Windows.
• Built-in macro language; extensible plugin architecture. Dozens of macros and plugins available.
• Plugins can be downloaded and installed from within jEdit using the "plugin manager" feature.
• Auto indent, and syntax highlighting for more than 130 languages.
• Supports a large number of character encodings including UTF8 and Unicode.
• Folding for selectively hiding regions of text.
• Word wrap.
• Highly configurable and customizable.
• Every other feature, both basic and advanced, you would expect to find in a text editor. See the Features page for a full list.