TextWrangler from BareBones Software just scored Retina Display support along with a few other BBEdit 10.5 features like the Go menu with Jump Point support, file change comparison, keyboard navigation designed for Windows converts, and more. TextWrangler isn't as full featured as BBEdit, but it's still a powerful code and text editor, and since it's free it won't put a strain on your wallet.
Check It Out: TextWrangler for Mac Goes Retina
