boostnote.io might be a good tool for you. Its basically a markdown renderer + code coloring with some extra search and other features. The first version is open source and I believe the second version also will be (but not positive). you can also store your folder of notes in a dropbox folder and get decent syncing out of the box. I've been using it for two years now and don't have any complaints. I will have to admit I haven't moved over to their second version yet so I might be missing something.