Buck2
Claim this toolA high-performance, extensible build system designed for large, multi-language monorepos.
Visit WebsiteFreeVisit Website
Tracked since2026
0 reviews trackedThe Bottom Line
Entry price
Free, no paid tier
Biggest pro
Optimized for very large, multi-language monorepos
Biggest con
Designed for large-scale use cases, potentially complex for smaller projects
TL;DR - Buck2
- Significantly faster build times compared to its predecessor, especially for large projects.
- Ensures reliable builds through hermetic rules and strict dependency enforcement.
- Highly extensible with all build rules written in Starlark, allowing custom rule definition.
Pricing: Free forever
Best for: Individuals & startups
What is Buck2?
Buck2 is a build system developed by Meta, specifically engineered to handle the complexities of very large monorepos that incorporate multiple programming languages such as C++, Python, Rust, Kotlin, and Swift. It is a complete rewrite of its predecessor, Buck1, aiming to improve speed, reliability, and extensibility while retaining target compatibility. Buck2 addresses the limitations of traditional build systems like Make when dealing with the scale and diversity of modern large-scale software development.
Key aspects of Buck2 include its ability to query build targets, support for remote execution to significantly increase parallelism, and multi-language composability, allowing different language components to interact seamlessly. It integrates with file watching services for efficient change detection and utilizes Starlark, a Python-like language, for defining build targets and advanced manipulations. Written in Rust, Buck2 prioritizes remote execution and features an entirely language-agnostic binary, with all rules defined externally in Starlark, enabling faster iteration and consistent feature availability across all rules.
Available on: Web
Pros & Cons
Pros
- Optimized for very large, multi-language monorepos
- Provides highly reliable and reproducible builds
- Allows for rapid iteration and customization of build rules
- Leverages remote execution for increased parallelism and efficiency
- Language-agnostic core binary ensures consistent feature access for all rules
Cons
- Designed for large-scale use cases, potentially complex for smaller projects
- Requires understanding of Starlark for custom rule development
Key Features
Faster build performanceHermetic build rules by defaultExtensible with Starlark-defined rulesRemote execution first architectureMulti-language composabilityDynamic (monadic) graph computation engineSupport for dynamic dependencies and anonymous targetsWritten in Rust for performance and absence of GC pauses
Pricing
Free
Buck2 is completely free to use with no hidden costs.
Reviews
$99Free with your review
Write a reviewReview Buck2, get a free AI guide
Share your experience and we will send you Improve Your Thinking Patterns Using ChatGPT, free.
Best Buck2 Alternatives
Top alternatives based on features, pricing, and user needs.
NXFreemium
Optimize builds, scale CI, and fix PRs faster with intelligent caching and AI-powered self-healing.
MakeFreemium
Build complex automations with a drag-and-drop visual builder
BazelFree
Build and test multi-language, multi-platform projects with speed and correctness.
TurborepoFree
Monorepo build system from Vercel
PantsFree
Accelerate development with a polyglot build system for large codebases.
PleaseFree
A high-performance, extensible, and reproducible cross-language build system.
Still deciding?
Most buyers shortlist 2 or 3 tools before committing. Pull a side-by-side comparison or browse the full alternatives shortlist below.
Explore More
Buck2 FAQ
How does Buck2 handle projects with multiple programming languages?
Buck2 is designed for multi-language composability, allowing different language components like C++, Python, Rust, Kotlin, and Swift to interact seamlessly within a single monorepo. Its language-agnostic core binary ensures consistent feature access across all build rules, regardless of the programming language.
Which teams would benefit most from using Buck2?
Buck2 is best suited for teams managing very large, multi-language monorepos due to its optimization for scale and complexity. It provides highly reliable and reproducible builds, which is crucial for large-scale software development.
How does Buck2 compare to Bazel?
Buck2, like Bazel, is a build system designed for large monorepos, but Buck2 is a complete rewrite of its predecessor, Buck1, aiming for improved speed, reliability, and extensibility. It prioritizes remote execution and uses Starlark for defining build targets, similar to Bazel's approach.
What kind of limitations might a user encounter with Buck2?
Buck2 is primarily designed for large-scale use cases, which might introduce complexity for smaller projects. Additionally, users will need to understand Starlark to develop custom build rules effectively.
How is Buck2 priced?
Buck2 is free to use, and no paid plan is required to access its features or capabilities.
Can Buck2 improve build times for large projects?
Yes, Buck2 leverages remote execution to significantly increase parallelism, which can lead to faster build times for large projects. It also integrates with file watching services for efficient change detection, further optimizing the build process.
How does Buck2 allow for customization of build rules?
Buck2 uses Starlark, a Python-like language, for defining build targets and advanced manipulations. This enables rapid iteration and customization of build rules, allowing users to tailor the build process to their specific needs.
Source: buck2.build