This is just a quick & dirty clone of the site ngl.link. It may not be as pretty, but it's much more private and quicker as well. The base idea is that you generate a site for yourself, and anyone with your ID can send you anonymous messages. You can self-host this as well pretty easily.
You'll need to generate a database secret at ./secrets/mongo_root_password.txt (see the docker-compose docs as well as the project's docker-compose.yml file). You can for example do so by running openssl -rand -out ./secrets/mongo_root_password.txt 64.
Then, just run docker-compose up -d to start.