Open-source alternatives to Railcar

Facilitates running Wasm / WASI workloads managed by containerd

crun is a low-level container runtime that implements the Open Container Initiative specification for managing the lifecycle of isolated processes. It provides the core mechanisms for container creation, execution, and deletion, ensuring compatibility across platforms through standardized lifecycle management. The project distinguishes itself by offering a shared C library that allows container runtime operations to be embedded directly into other compiled applications. It further extends execution capabilities through specialized handlers that enable the deployment of containers within isola

Libpod is a container management library for running and controlling the lifecycle of Open Container Initiative compliant containers and images across different storage backends. It provides a programmatic interface for the remote control and automation of container environments. The project enables the coordination of multiple containers into pods that share network namespaces and other shared resources. It supports rootless container execution by using user namespaces to launch containers without administrative privileges. The library covers a broad range of system operations, including im

Podman is a container engine designed for managing containerized applications and images without the need for a persistent background daemon. By utilizing a fork-exec process model, it executes container management commands as direct child processes of the host system, ensuring that container lifecycles are handled through standard host-level process control. The project distinguishes itself through a focus on rootless security and cross-platform compatibility. It employs user namespace mapping to allow unprivileged users to manage isolated workloads without requiring administrative system ac

Youki is an OCI container runtime written in Rust. It implements the Open Container Initiative runtime specification to manage the lifecycle of containerized processes and ensure compatibility with standard container images and engines. The runtime is designed for memory safety and supports rootless container execution, allowing containers to run as non-root users to reduce security risks and limit privilege escalation. It provides core container management capabilities, including spawning and managing OCI containers. This is achieved through Linux namespace isolation, cgroup-based resource

rkt is a secure Linux container engine and pod-native container manager. It provides a composable execution environment for launching and managing isolated application containers on Linux, serving as a runtime designed around open industry standards for image formats and networking interfaces. The system is distinguished by a pod-native execution model that groups multiple containers and shared resources into single, self-contained units. It utilizes pluggable execution engines to provide secure isolation, including the use of hardware-based virtualization to create security boundaries betwee

CRI-O is an open-source container runtime that implements the Kubernetes Container Runtime Interface (CRI) to manage container images, pods, and containers on cluster nodes using OCI-compatible runtimes. It serves as a node-level container manager that handles image pulling, container lifecycle, and resource monitoring for Kubernetes clusters, running containers according to the Open Container Initiative specifications. The runtime distinguishes itself through live configuration reloading that applies changes to runtime definitions, registry mirrors, and TLS certificates without restarting th

Spin is a WebAssembly serverless framework and development toolchain for building and running portable microservices. It functions as an event-driven orchestrator and runtime that executes WebAssembly components, allowing developers to map HTTP requests, Redis messages, and cron schedules to specific modules. The project distinguishes itself by implementing a Wasm-based AI inference gateway, enabling components to perform model inference and generate text embeddings. It utilizes the WebAssembly Component Model and WASI for language-agnostic composition and portable host interfacing, while emp

Firecracker is a virtual machine monitor that leverages hardware-assisted virtualization to create and manage isolated execution environments. It functions as a lightweight runtime designed to launch virtual machines with minimal memory overhead and near-instantaneous startup times, providing the security of traditional hardware virtualization with the efficiency of containerized workloads. The project distinguishes itself through a security-focused architecture that enforces strict process boundaries using system-level barriers and restricted user privileges. It minimizes the attack surface

firecracker-containerd enables containerd to manage containers as Firecracker microVMs

img is a collection of toolsets for building, managing, and manipulating OCI compliant container images. It functions as an image build tool and registry client, providing the capabilities to create images from configuration files, push and pull images to remote registries, and extract image layers into root filesystems or archives. The project distinguishes itself through support for multi-platform builds using hardware emulators and the ability to perform unprivileged container builds via namespace-based process isolation and user ID mapping. It also includes a cross-platform binary compile

This project is a secure container runtime that provides strong isolation for application workloads by implementing a userspace kernel. By intercepting system calls and executing them within a memory-safe, restricted environment, it minimizes the attack surface exposed to the host kernel. It functions as a drop-in engine for standard container orchestration platforms, ensuring compatibility with industry-standard runtime specifications while maintaining a hardened execution boundary. The runtime distinguishes itself through its ability to virtualize core system resources, including an indepen

lmctfy (pronounced l-m-c-t-fi, IPA: /ɛlɛmsitifаɪ/) is the open source version of Google’s container stack, which provides Linux application containers. These containers allow for the isolation of resources used by multiple applications running on a single machine. This gives the applications the…

Agones is a Kubernetes game server orchestrator designed for deploying, scaling, and managing dedicated multiplayer game server processes across a distributed cluster. It provides the core infrastructure needed to provision individual or grouped server processes to support real-time multiplayer gaming sessions. The system includes a fleet manager to automate the lifecycle of server groups based on player demand and a health monitor to track the connectivity and operational status of active processes. It integrates with cluster autoscalers to synchronize server resource requirements with cloud

HyperContainer Daemon

runV is a hypervisor-based runtime for OCI.

Build and run layered root filesystems.

A basic user tool to execute simple docker containers in batch or interactive systems without root privileges.

A multi-sandbox container runtime that provides cloud-native, all-scenario multiple sandbox container solutions.

LXC is an OS-level virtualization framework and Linux container manager used to run multiple isolated Linux systems on a single host. It functions as a kernel namespace orchestrator and unprivileged container runtime, allowing for the creation and management of system containers without the overhead of a hypervisor. The project provides unprivileged container execution by mapping container root users to unprivileged host users to prevent host system access. It ensures security through system call filtering and root user isolation, enabling containers to run without requiring host root privile