Janus Notes is an Open Source note-taking program that seriously respects your right to privacy. It supports plain-text notes, and markdown with preview and free-format attachments. The notes can be seamlessly shared among different Macs and to your iDevices using Dropbox. Or not. It's your call. Your notes can be encrypted on your Dropbox so as to avoid eavesdroppers. This app understands that note-taking is a very personal thing, and it tries very hard to keep your data as safe as possible. The application has no access to your Dropbox beside the specific folder that we use for storing notes, and it is fully sandboxed. We have no access to anything other than the Dropbox folder you choose and the attachments you added to the notes (a copy of them, stored with the notes). The source code is available (MIT licensed) on GitHub under ilTofa/janusnotes.
Your data is safe.