Fossbill is a minimalist tool to edit, generate and send bills to emails. It is FOSS as it is licenced under AGPL3. Its source code can be pulled here.
It is really easy to self-host an instance of Fossbill. Feels free to check the documentation to configure it to suits your needs.
Fossbill is free as in freedom, but this hosted instance cost 10 euros/month. This support the development of the tool, and encourage me to build new ones.
I am Willow Barraco, a french developper girl and I live near Lyon. I write free and open-source softwares. I am very active in the Alpine Linux / Postmarketos ecosystem as a sxmo co-maintainer. Here my website and my projects.