Siwapp
Online Invoice Management
The unofficial port of the old 0.4.x version to Symfony 3.x and PHP 7.x.
The initial siwapp project was based on Symfony version 1, but the founders decided to switch the project from PHP to Ruby on Rails, something you can find here: https://github.com/siwapp/siwapp
You can find the documentation of this project in the github wiki here: https://github.com/siwapp/siwapp-sf3/wiki