Article about this repository: dewep.net/realisations/en/pokemon-go-how-i-changed-my-geolocation.
You need to install NodeJS and npm. After it, run the command npm install (in the server directory).
To run the server: node app.js
You need to install Android Studio (or other software allowing to compile and run an Android application on your phone). Import the project (android directory).
You need to run the application on your phone (in debug mode at least one time in order to see the application in the setting Select mock location app, in the developers options).
If you want to use this application with the Pokemon GO, you need to install and configure XposedInstaller and Mock Mock Locations (cf section Android Installation on my article).
Go on http://127.0.0.1:5000 to see the web interface. Run the Android application, and start the service with the simulation identifier displayed on the web interface.