BuildKit

Overview

BuildKit pairs the buildkitd daemon with the buildctl client. Builds are represented in LLB, a vendor-neutral format for process dependency graphs that supports concurrent execution and cache reuse. Docker Engine 23.0 and later use Buildx and BuildKit by default for docker build, so Docker users may already encounter it as part of their workflow. The project is Apache-2.0 licensed and is used by projects including Moby, Docker, Tekton Pipelines, Gitpod and Dagger.

Key features

Flexible builds and reusable work

Frontends translate build definitions into LLB, with support for Dockerfiles and other LLB languages. Concurrent dependency resolution, instruction caching, and cache import and export can cut repeated build work. Cache exporters include inline, registry, local-directory and GitHub Actions options; GitHub Actions, S3 and Azure Blob cache options are marked experimental, making them less suitable as a critical dependency when stability matters.

Outputs include images, local directories, tarballs, Docker tarballs and OCI tarballs. Automatic garbage collection helps manage accumulated build data, while nested jobs, pluggable architecture and distributable workers give teams room to shape the build system around their infrastructure. The daemon supports OCI (runc) and containerd worker backends.

Execution and security

Rootless execution is supported, and BuildKit describes itself as secure by default and usable with untrusted sources. With the default daemon configuration, the API is confined from the host filesystem outside BuildKit’s state directory; application and frontend containers cannot access the host system, invoke privileged system calls or directly use external devices. This is a useful boundary for build workloads, though it does not replace an operator’s responsibility to configure and run the daemon appropriately.

Pricing

BuildKit is free under the Apache License 2.0: 0.00 USD per free, perpetual, worldwide, non-exclusive, no-charge and royalty-free. There are no paid tiers or seat and usage caps in the stated plan, so it suits teams that can operate their own build infrastructure and do not need a hosted service. The cost is operational effort rather than a subscription.

Platforms

BuildKit supports Linux, Windows and macOS, with binaries for all three and self-hosted deployment. Rootless mode and Windows containers are supported. The important macOS caveat is that the unofficial Homebrew formula omits the buildkitd daemon; Lima running a Linux VM is one suggested way to provide it. The daemon exposes a gRPC API at /run/buildkit/buildkitd.sock by default and can also use TCP sockets.

Who it's for

BuildKit fits developers and platform teams building container-oriented pipelines who value cache control, multiple output formats and support for different build-definition frontends. Its use across Moby, Docker, Tekton Pipelines, Docker buildx, Gitpod, Dagger and other projects points to a place in both local development and CI workflows. It is less compelling for people seeking a turnkey desktop app or managed build service: BuildKit is a daemon-and-client toolkit that the user must integrate and operate.

Pros and cons

• Pros: Concurrent resolution and instruction caching can avoid duplicated work; cache import and export enable reuse across environments.
• Pros: Dockerfile and other LLB frontends, several worker backends and varied export formats accommodate different pipelines.
• Pros: Free Apache-2.0 licensing and rootless execution make it practical for self-managed builds with cost and privilege constraints.
• Cons: macOS Homebrew does not provide the daemon, so Mac users need another route such as a Linux VM.
• Cons: Some cache options are experimental, a drawback for teams depending on those backends in important workflows.
• Cons: The daemon/client architecture requires setup and operation rather than offering a managed workflow.

Alternatives

Docker Desktop is the more natural choice for readers who want a freemium option across desktop platforms; its free Docker Personal plan is limited to one user, one Docker Scout-enabled repository, 100 Docker Hub pulls per hour and one private Docker Hub repository.

Incus is another free Apache 2 licensed option for readers seeking an alternative in this wider container and infrastructure space. LXD offers open-source KVM-based virtual machines and system containers with self-hosted deployment, so choose it when those are the workloads you need. Apptainer is a free open-source container platform, with commercial support available through partners.

gVisor is a Linux-only open-source sandbox requiring Linux 5.6 or later on x86_64 or ARM64; it is the alternative to consider when that sandbox role is the priority. Podman provides free container, pod and image management alongside Podman Desktop. containerd is a free Apache 2.0-licensed open-source container runtime, while crun is a free OCI container runtime with source builds and release binaries.

Browse Container Build Tools for more build-focused options, or Container Engines for tools centered on running containers.

Verdict

Choose BuildKit if you want a free, extensible build toolkit with serious caching, multiple outputs and control over execution. Its main advantage is flexibility across build definitions and infrastructure; look elsewhere if you need a managed workflow or a straightforward macOS daemon installation.