With a type expander like Typinator (much less buggy than TextExpander), Smultron competes with BBEdit. Advantage - your sniplets are accessible in all your other text editing applications (including browsers).

Brilliant, simple, a rest for weary eyes. Light footprint.

I own BBEdit but plan to do a lot of my work in Smultron going forward.

Great split screen, tab and preview functions.

This is not freeware but donationware. Donate and enjoy software without annoying installation and licensing routines.