Here are some nice free apps for OS X.
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TextMate. The handy but expensive text editor (~53 USD for a single licence) has gone open source and free since TextMate 2 (released under GNU General Public license Ver 3), which has tons of improvements as compared with Ver. 1.5, including the support for East Asian languages. The latest builds can be downloaded from here. TextMate was created and has been developed by Allan Odgaard.