List of free container stuff for developerππ½
If you're looking for all programming tools around container (not just free). Check this page List of container Programming Tools

Open Source Container
Portainer
Open Source Container Management GUI for Kubernetes, Docker, Swarm
Tag: container, kubernetes
Open Source Container Management

Container Registry
A no frills Harbor based Container Registry Service for teams, individuals and Software Vendor looking for ways to distribute images instead of ZIP files..
Tag: container, container-registry, docker, storage
1 GB free storage for unlimited private container images
Kubernetes
Kubernetes is an open source container orchestration engine for automating deployment, scaling, and management of containerized applications.
Tag: container, kubernetes
Open Source Container Orchestration