jEdit

jEdit is a mature programmer's text editor with hundreds of person-years of development.

jEdit is a mature programmer's text editor with hundreds (counting the time developing plugins) of person-years of development behind it. To download, install, and set up jEdit as quickly and painlessly as possible, go to the Quick Start page. While jEdit beats many expensive development tools for features and ease of use, it is released as free software with full source code, provided under the terms of the GPL 2.0. The jEdit core, together with a large collection of plugins is maintained by a world-wide developer team.