We'd like to clarify two issues related to Unsub and open source.
Open Source but not Open Contribution
Unsub does not take contributions from outside contributors. We are a small team and it takes time to manage community contributions. We are however always eager to hear user feature requests and bug reports to improve the product.
The creator of the database BoltDB has an explanation of why his newer project litestream is open source BUT not open contribution.
Open Source but cannot be self-hosted
Many open source projects can be run by anyone, anywhere (server, local machine, etc.) - anyone can get the same outcome running it on their own as the owners of the project. So why would a project be open source but not be able to be self-hosted?
For Unsub, there is a significant component of user supplied data, as well as data curated in house, making it only possible to operate as a hosted application.