Apptainer vs Shifter
Apptainer
apptainer.orgShifter
github.comSide by side
| Figure | Apptainer | Shifter |
|---|---|---|
| Price from | Free | — |
| Free plan | Yes | — |
| Free trial | — | — |
| Open source | — | — |
| Windows | Yes | — |
| macOS | Yes | — |
| Linux | Yes | Yes |
| API | Yes | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 1 | 0 |
| Spec score · Container Engines | 8.9 (#1) | 7.0 (#27) |
| Purpose | Apptainer creates and runs containers that package software for portability and reproducibility. | Shifter enables HPC systems to run end-user container images, including Docker images. |
| Security model | By default, users retain the same identity inside the container and cannot gain additional host privileges. | Shifter uses privileged operations to set up containers; its security documentation says processes launched in a container have privileges stripped and should not be able to re-escalate. |
| Support | Free support resources include Slack, a mailing list, and GitHub, while commercial support and services are offered through CIQ. | The project README directs users to its Google Groups email list for updates and community support. |
Plans
In their own words
Apptainer
Apptainer is a free container platform for creating and running portable, reproducible workloads, with a focus on shared systems and high-performance computing. It packages containers as immutable, single-file Singularity Image Format (SIF) images designed for transport and sharing. By default, users retain the same privileges inside and outside containers. Images can be signed and verified with PGP keys, PEM keys or X.509 certificates, and encrypted containers can run without writing decrypted contents to disk. Apptainer imports containers from OCI registries and aims to support most Docker Hub containers without changes. It can expose host resources such as GPUs, high-speed networks and parallel filesystems, and supports NVIDIA CUDA, AMD ROCm, Intel Gaudi and OCI Container Device Interface accelerators. Running Apptainer requires Linux; Windows and macOS need a Linux virtual machine, with Windows also listed via WSL2. Root access is unnecessary when user namespaces are available. Full functionality requires kernel support for FUSE and unprivileged user namespaces. Community support includes Slack, Google Groups and GitHub, with commercial services through CIQ.