Ranked in these QuestionsQuestion Ranking
Pro Open source
TagSpaces is free and open source making it easily extendable with the help of extensions.
Pro No cloud
TagSpaces is running completely offline, sending no data to any cloud based service, unlike many Evernote alternatives.
Pro No web service or database lock in
The backend is simply the directory and file structure on your harddrive.
Pro Your can choose your cloud file storage
Using only files and no databases let's you make the decision with which cloud file sync service to use, making sure your notes are made available on other devices and platforms. It works great with Owncloud, Nextcloud, Dropbox or Google Drive.
Con It renames your files in order to tag them
The positive side of this drawback is that this way the tags are easily transferred to other platforms by simply syncing them.