FTLDNS and Unbound Combined For Your Own All-Around DNS Solution
Android app: https://f-droid.org/packages/info.varden.hauk/
Hauk is a fully open source, self-hosted location sharing service. Install the backend code on a PHP-compatible web server, install the companion app on your phone, and you're good to go!
Turtl lets you take notes, bookmark websites, and store documents for sensitive projects. From sharing passwords with your coworkers to tracking research on an article you're writing, Turtl keeps it all safe from everyone but you and those you share with.
Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, can be copied, tagged and modified either from the applications directly or from your own text editor. The notes are in Markdown format.
Rclone is a command line program to sync files and directories to and from cloud services.
Crypt is the encryption feature of rclone.