Apptainer
- 1Runs onAPI, Linux, Mac, self-hosted, Windows
- 2CostsFree plan
- 3Rootless modeYes
- 4Image buildingYes
- 5Windows containersNo
- 6Image formatboth
- 7Runtime interfaceother
- 8Supported host OSLinux; Windows via WSL2; macOS via Linux VM
Overview
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.
Who it is for
Apptainer is designed for shared systems and HPC environments, including complex applications on clusters. It suits users who can run Linux directly or through a virtual machine on Windows or macOS.
What is good
- Free container platform
- Immutable single-file SIF images
- Supports GPU and other host resources
- Encrypted containers can run without disk decryption
- Root access unnecessary with user namespaces
What to know first
- Linux required to run Apptainer
- Windows and macOS require a Linux virtual machine
- Full functionality requires FUSE and unprivileged user namespaces
Verdict
Apptainer focuses on portable containers for shared systems and HPC, with SIF images, signing and encrypted execution. Its Linux requirement and kernel prerequisites matter when planning deployment.
Apptainer plans and pricing
All plansCompared on container engines
- Free plan
- Yesapptainer.org
- Rootless mode
- Yesapptainer.org
- Image building
- Yesapptainer.org
- Windows containers
- Noapptainer.org
- Image format
- bothapptainer.org
- Runtime interface
- otherapptainer.org
- Supported host OS
- Linux; Windows via WSL2; macOS via Linux VMapptainer.org
Facts
- Purpose
- Apptainer simplifies creation and execution of containers for portability and reproducibility.apptainer.org · 1 Oct 2026
- Primary users
- Apptainer is designed for shared systems and high-performance computing environments.github.com · 1 Oct 2026
- Container format
- Apptainer produces immutable single-file Singularity Image Format (SIF) images.apptainer.org · 1 Oct 2026
- Security model
- Users remain the same inside and outside containers and cannot gain additional host privileges by default.apptainer.org · 1 Oct 2026
- Encryption
- Apptainer supports encrypted containers that can run without decrypting contents to disk.apptainer.org · 1 Oct 2026
- Signing
- SIF images support cryptographic signing and verification with PGP keys, PEM keys, or X.509 certificates.apptainer.org · 1 Oct 2026
- OCI compatibility
- Apptainer can import containers from OCI registries and aims for compatibility with Docker containers.apptainer.org · 1 Oct 2026
- GPU support
- Apptainer supports NVIDIA CUDA, AMD ROCm, Intel Gaudi, and OCI Container Device Interface accelerators.apptainer.org · 1 Oct 2026
- Host integration
- Apptainer provides access to GPUs, high-speed networks, parallel filesystems, and other host resources by default.github.com · 1 Oct 2026
- Installation requirement
- A Linux system is required to run Apptainer, and root access is unnecessary when user namespaces are available.apptainer.org · 1 Oct 2026
- Support
- Support includes Slack, Google Groups, GitHub, and commercial services through CIQ.apptainer.org · 1 Oct 2026
- Security response
- The Apptainer Technical Steering Committee accepts vulnerability reports at [email protected] and documents vulnerabilities through CVEs.apptainer.org · 1 Oct 2026
- Governance
- Apptainer is hosted by the Linux Foundation and was formerly known as Singularity.linuxfoundation.org · 1 Oct 2026
- Target users
- The project was created for complex applications on HPC clusters and is used across academia and industry.apptainer.org · 2 Oct 2026
- Single-file format
- Containers use the single-file SIF format, which is designed to be transported and shared.apptainer.org · 2 Oct 2026
- Signatures and encryption
- Apptainer supports cryptographic signatures, immutable container images, and in-memory decryption.apptainer.org · 2 Oct 2026
- Docker compatibility
- Apptainer can import containers from OCI registries and aims to support pulling, running, and building most Docker Hub containers without changes.apptainer.org · 2 Oct 2026
- Secrets integration
- Apptainer can encrypt containers and integrate with Vault and other secret-management platforms.apptainer.org · 2 Oct 2026
- Linux requirement
- Apptainer can be installed on modern Linux distributions, while Windows and macOS require a Linux virtual machine to run it.apptainer.org · 2 Oct 2026
- Linux requirements
- Full functionality requires kernel support for FUSE and unprivileged user namespaces; some features require additional software such as BuildKit or IPFS.apptainer.org · 2 Oct 2026
- Security reporting
- The Technical Steering Committee manages project security, and the policy directs vulnerability reports through private contact with the project.apptainer.org · 2 Oct 2026
- Project steward
- The project site says Apptainer is established as a Series of LF Projects LLC.apptainer.org · 2 Oct 2026
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Sources
- apptainer.org· checked 1 Oct 2026
- github.com/apptainer/apptainer· checked 1 Oct 2026
- apptainer.org/docs/user/latest/quick_start.html· checked 1 Oct 2026
- apptainer.org/docs/user/latest/security.html· checked 1 Oct 2026
- apptainer.org/docs/user/latest/· checked 1 Oct 2026
- apptainer.org/docs/user/latest/signNverify.html· checked 1 Oct 2026
- apptainer.org/docs/user/latest/gpu.html· checked 1 Oct 2026
- apptainer.org/support/· checked 1 Oct 2026
- apptainer.org/security-policy/· checked 1 Oct 2026
- linuxfoundation.org/press/press-release/new-linux-foundatio· checked 1 Oct 2026
- apptainer.org/docs/user/latest/introduction.html· checked 2 Oct 2026
- apptainer.org/docs/admin/latest/installation.html· checked 2 Oct 2026