A non-exhaustive list of containerd adopters is provided below.
Docker/Moby engine - Containerd began life prior to its CNCF adoption as a lower-layer
runtime manager for runc processes below the Docker engine. Continuing today, containerd
has extremely broad production usage as a component of the Docker engine
stack. Note that this includes any use of the open source Moby engine project;
including the Balena project listed below.
faasd by OpenFaaS - faasd in an Open Source project for serverless functions. It takes the same OpenFaaS components that usually run on Kubernetes and instead launches containers directly on a single host using CNI for networking. It's ideal for edge and for deploying functions without having to think about managing and maintaining Kubernetes.
IBM Cloud Kubernetes Service (IKS) - offers containerd as the CRI runtime for v1.11 and higher versions.
IBM Cloud Private (ICP) - IBM's on-premises cloud offering has containerd as a "tech preview" CRI runtime for the Kubernetes offered within this product for the past two releases, and plans to fully migrate to containerd in a future release.
Google Container-Optimized OS (COS) - Container-Optimized OS is a Linux Operating System from Google that is optimized for running containers. COS has used containerd as container runtime when containerd was part of Docker's core container runtime.
Google Cloud Kubernetes Engine (GKE) - containerd has been offered in GKE since version 1.14 and has been the default runtime since version 1.19. It is also the only supported runtime for GKE Autopilot from the launch. More details
AWS Fargate - uses containerd + Firecracker (noted below) as the runtime and isolation technology for containers run in the Fargate platform. Fargate is a serverless, container-native compute offering from Amazon Web Services.
Amazon Elastic Kubernetes Service (EKS) - EKS optionally offers containerd as a CRI runtime starting with Kubernetes version 1.21. In Kubernetes 1.22 the default CRI runtime will be containerd.
Bottlerocket - Bottlerocket is a Linux distribution from Amazon Web Services purpose-built for containers using containerd as the core system runtime.
Cloud Foundry - The Guardian container manager for CF has been using OCI runC directly with additional code from CF managing the container image and filesystem interactions, but have recently migrated to use containerd as a replacement for the extra code they had written around runC.
Alibaba's PouchContainer - The Alibaba PouchContainer project uses containerd as its runtime for a cloud native offering that has unique isolation and image distribution capabilities.
Rancher's k3s project - Rancher Labs k3s is a lightweight Kubernetes distribution; in their words: "Easy to install, half the memory, all in a binary less than 40mb." k8s uses containerd as the embedded runtime for this popular lightweight Kubernetes variant.
Rancher's Rio project - Rancher Labs Rio project uses containerd as the runtime for a combined Kubernetes, Istio, and container "Cloud Native Container Distribution" platform.
Balena - Resin's Balena container engine, based on moby/moby but for edge, embedded, and IoT use cases, uses the containerd and runc stack in the same way that the Docker engine uses containerd.
LinuxKit - the Moby project's LinuxKit for building secure, minimal Linux OS images in a container-native model uses containerd as the core runtime for system and service containers.
BuildKit - The Moby project's BuildKit can use either runC or containerd as build execution backends for building container images. BuildKit support has also been built into the Docker engine in recent releases, making BuildKit provide the backend to the docker build command.
Azure Kubernetes Service (AKS) - Microsoft's managed Kubernetes offering uses containerd for Linux nodes running v1.19 and greater, and Windows nodes running 1.20 and greater. More Details
Amazon Firecracker - The AWS Firecracker VMM project has extended containerd with a new snapshotter and v2 shim to allow containerd to drive virtualized container processes via their VMM implementation. More details on their containerd integration are available in their GitHub project.
Kata Containers - The Kata containers lightweight-virtualized container runtime project integrates with containerd via a custom v2 shim implementation that drives the Kata container runtime.
D2iQ Konvoy - D2iQ Inc Konvoy product uses containerd as the container runtime for its Kubernetes distribution.
Inclavare Containers - Inclavare Containers is an innovation of container runtime with the novel approach for launching protected containers in hardware-assisted Trusted Execution Environment (TEE) technology, aka Enclave, which can prevent the untrusted entity, such as Cloud Service Provider (CSP), from accessing the sensitive and confidential assets in use.
VMware TKG - Tanzu Kubernetes Grid VMware's Multicloud Kubernetes offering uses containerd as the default CRI runtime.
VMware TCE - Tanzu Community Edition VMware's fully-featured, easy to manage, Kubernetes platform for learners and users. It is a freely available, community supported, and open source distribution of VMware Tanzu. It uses containerd as the default CRI runtime.
Talos Linux - Talos Linux is Linux designed for Kubernetes – secure, immutable, and minimal. Talos Linux is using containerd as the core system runtime and CRI implementation.
Deckhouse - Deckhouse Kubernetes Platform from Flant allows you to manage Kubernetes clusters anywhere in a fully automatic and uniform fashion. It uses containerd as the default CRI runtime.
_Actuated - Actuated is a platform for running self-hosted CI in securely-isolated Firecracker VMs. Actuated uses containerd's image pulling facility to distribute and update the root filesystem for VMs for CI agents.
Other Projects - While the above list provides a cross-section of well known uses of containerd, the simplicity and clear API layer for containerd has inspired many smaller projects around providing simple container management platforms. Several examples of building higher layer functionality on top of the containerd base have come from various containerd community participants: