OpenTodoList

OpenTodoList is a todo list and note taking application. Organize todo lists,
notes and images in libraries, which can be stored either completely local
on the device you are working on (and hence ensure no information leaks out
to untrusted third parties) or use the built in synchronization features which
allows you to synchronize your libraries across devices using your self-hosted
NextCloud or ownCloud server, other WebDAV servers or Dropbox. In addition, a library
is just a directory holding the items of your library as simple files - this
allows you to use any kind of third party synchronization tool
to sync your information.