Along the same lines as the TW5-browser-nativefilesaver that @Mohammad referenced, I like to use TiddlyStow: Tiddlystow a(nother) native file saver
It uses the same mechanism but you use it by opening the TiddlyStow html file and then load a single-file Tiddlywiki through that loader. Then you can save in place (at least in Chorme-based browsers).
Just another option.
/Mike