Docker Swarm is described as 'Is native clustering for Docker. It allows you create and access to a pool of Docker hosts using the full suite of Docker tools. Because Docker Swarm serves the standard Docker API, any tool that already communicates with a Docker daemon can use Swarm to' and is an app in the network & admin category. There are more than 10 alternatives to Docker Swarm for a variety of platforms, including Linux, Self-Hosted, Web-based, Windows and Mac apps. The best Docker Swarm alternative is Kubernetes, which is both free and Open Source. Other great apps like Docker Swarm are Rancher, Dokku, DDEV and Rancher Desktop.
It doesn't seem to be an alternative to the Docker Swarm. It is a PostgreSQL distribution for Kubernetes.