Apptainer vs Charliecloud
Apptainer
apptainer.org
Charliecloud
charliecloud.ioSide by side
| Figure | Apptainer | Charliecloud |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Windows | Yes | — |
| macOS | Yes | — |
| Linux | Yes | Yes |
| API | Yes | — |
| Self-hosted | Yes | Yes |
| Plans published | 1 | 1 |
| Spec score · Container Engines | 8.9 (#1) | 7.9 (#10) |
| Spec score · Container Runtime Software | 8.9 (#1) | 8.0 (#12) |
| Purpose | Apptainer creates and runs containers that package software for portability and reproducibility. | Charliecloud is a lightweight, fully unprivileged, open source container implementation for high performance computing applications. |
| Support | Free support resources include Slack, a mailing list, and GitHub, while commercial support and services are offered through CIQ. | Users can report bugs or request features through the GitLab project and can get usage help through mailing lists and chat channels. |
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.
Charliecloud
Charliecloud is free, open-source container software for high-performance computing on Linux. It runs containers without privileged operations or daemons by using Linux user namespaces, with minimal configuration changes on computing-center resources. Users can build images, push and pull them to registries, and use accelerators such as GPUs. Its layer-free build cache is based on Git rather than union-mount filesystems and tarballs, and Dockerfiles are parsed with a formal grammar. The ch-image tool supports registry authentication and registries including GitLab Container Registry. At runtime, ch-run can inject host resources through the Container Device Interface, including NVIDIA GPUs and Cray networking. Installation is available from a release tarball, Git checkout, Spack, or Fedora/EPEL. Charliecloud requires Linux user namespaces and has been run on x86-64, ARM, and Power; current testing covers x86_64 and ARM. It is distributed under Apache License, Version 2.0. The project supports only the current release and provides no internal security boundary.