Docker (Recommended method):
Docker Image by linuxserver.io, thanks guys!
Text Guide | Video Guide
Download war file
Installation script / Control Panel & Installer (BETA)
Instructions for Linux coming soon but if you are running Linux I am guessing all you need to know is "java -jar booksonic.war -Dserver.port=4040", yup, it's as simple as that now.
Want to install Booksonic in the cloud instead of your own hardware?
I recommend renting a VPS from Interserver or Contabo and installing booksonic there.
Use coupon code BOOKSONIC on Interserver to get the first month for just 1 cent.
OBS! These are referral links, that means that I (Booksonic dev) will be receiving a small amount of money if you click on them and buy anything. While that is the case I will only ever recommend VPS providers that I am personally using and can vouch for.
Build from source (Free): Link
This option is totally free but you will need to re-build it if you want to update it. This one is recommended if you want to make changes to the app or don't have the play store on your phone.
Google Play (~$3): Link
This one is recommended if you just want to use the app and never have to worry about updating it since it comes with automatic updates