Overview

BuildKit separates the buildkitd daemon from 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 many Docker users encounter it as part of their existing workflow rather than as a separate tool. The project is licensed under Apache-2.0 and identifies users including Moby, Docker, Tekton Pipelines, Gitpod, Dagger, and Depot.

Key features

Extensible, cache-aware builds

Frontends translate build definitions into LLB; Dockerfiles and other LLB languages are supported. Concurrent dependency resolution, instruction caching, and cache import and export help reduce repeated work. Cache exporters include inline, registry, local directory, and GitHub Actions. The GitHub Actions, S3, and Azure Blob cache options are experimental, so workflows that depend on them carry more uncertainty than those using the established exporters.

Build results can be exported as images, local directories, tarballs, Docker tarballs, or OCI tarballs. That range is useful when a pipeline needs more than a container image, while automatic garbage collection helps manage accumulated build data. Nested build jobs, pluggable architecture, and distributable workers give teams further room to shape their build pipelines.

Workers, permissions, and isolation

The daemon supports OCI (runc) and containerd workers, and BuildKit can execute without root privileges. Its default security model limits API access to the BuildKit state directory and prevents application and frontend containers from accessing the host system, privileged system calls, or external devices directly. Those controls make it suitable for builds involving untrusted sources, though they do not remove the operational responsibility of running and configuring the daemon.

API and integrations

The daemon exposes a gRPC API, using /run/buildkit/buildkitd.sock by default, and can also listen on TCP sockets. The project lists integrations and users across Docker, Moby, Tekton Pipelines, Docker buildx, Gitpod, Dagger, and other projects. This makes BuildKit a natural fit for teams extending existing container or CI infrastructure rather than seeking a self-contained hosted build service.

Pricing

BuildKit is free under the Apache-2.0 license: the BuildKit plan is free, with perpetual, worldwide, non-exclusive, no-charge, royalty-free terms. There are no paid tiers or plan quotas to weigh. The trade-off is operational rather than financial: teams run the daemon and client within their own build environment.

Platforms

BuildKit supports Linux, Windows, and macOS, with binaries for all three, as well as API and self-hosted use. The macOS caveat matters: the unofficial Homebrew formula does not include the buildkitd daemon. The project gives running it in a Linux VM through Lima as an example, which adds setup compared with using Docker Engine 23.0 or later, where BuildKit is enabled by default for docker build. Windows containers and rootless mode are supported.

Who it's for

BuildKit suits developers and platform teams that need configurable, cache-conscious builds, multiple output formats, or integration with existing container and CI tooling. Its free, permissively licensed distribution is attractive for self-hosted pipelines, and the ability to run without root privileges is useful where build permissions need to be constrained. It is a weaker fit for readers who want a managed build service or a straightforward macOS installation without a separate daemon setup.

Pros and cons

Broad build flexibility: Dockerfiles and other LLB frontends, multiple worker backends, and several output formats support varied pipeline designs.
Reusable work: Concurrent dependency resolution, instruction caching, and cache import and export can avoid rebuilding unchanged work.
Useful isolation controls: Rootless execution and default host-access restrictions help limit what builds can reach.
Self-managed operation: The daemon-and-client architecture puts setup and operation on the team rather than offering a hosted workflow.
Mac setup hurdle: The unofficial Homebrew formula omits the daemon, so macOS users need another way to run it, such as a Linux VM.
Experimental cache choices: GitHub Actions, S3, and Azure Blob cache options are marked experimental, a concern for pipelines that rely on them.

Alternatives

Dagger is worth considering for teams that want a freemium option with a free Individual plan for one user and 1,000,000 monthly events, plus a one-month run history and community support.
Garden may suit readers seeking a freemium option with a free tier, while its Enterprise plan includes secrets management, RBAC, and self-hosting.
Jib is a free alternative focused on open-source container building tools for Java.
ko is a free open-source container image builder for Go.
Tilt is a free, Apache-2.0-licensed option.
Cloud Native Buildpacks Pack offers a free CLI and Go library, with no paid plans.
Depot is a paid alternative with a Developer plan at 20.00 USD per month, billed monthly, including one user and build-minute allowances.
Kaniko is a free option for building container images from Dockerfiles, distributed as container images.

Browse more options in Container Build Tools and Container Engines.

Verdict

Choose BuildKit if you need a free, flexible engine for self-managed container builds, especially when cache reuse, multiple frontends, or constrained execution matter. Its strongest reason to choose it is the control its extensible architecture gives a build pipeline. Look elsewhere if you want managed builds or a simpler macOS installation: the daemon remains yours to run, and Homebrew does not supply it.

	BuildKit	KIWI NG
Free plan	Yes	Yes
Free trial		No
Paid from	Free	Free
Platforms	api, Linux, macOS, self-hosted, Windows	Linux, self-hosted
Free plan	Yes	Yes
Rootless mode	Yes
Image building	Yes
Windows containers	Yes
Image format	both
Runtime interface	other
Supported host OS	Linux, Windows, macOS
Build method		daemonless
Multi-architecture builds		Yes
Build cache backends		local

BuildKit vs KIWI NG

BuildKit

KIWI NG