Apptainer is a container system for high performance computing (HPC).Formerly known as Singularity. It is used to build and run Linux containers, packaging software, libraries, and runtime compilers in an isolated environment. In addition, Apptainer containers can be easily deployed and run on different computer systems. It is designed to execute applications with bare metal performance while maintaining a high level of security, portability, and repeatability.

Apptainer is an open source project with a growing community and an expanding user base.

The main features of Apptainer are:

• It supports public/private key signatures for trust;
• It is compatible with Docker and the Open Container Initiative;
• portability;
• The container runs rootless to prevent privilege escalation;
• Leverage GPUs, FPGAs, high-speed networks, and file systems;
• Easy to use.