Bazel vs Buck2
Bazel
bazel.build
Buck2
buck2.buildSide by side
| Figure | Bazel | Buck2 |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| Self-hosted | — | Yes |
| Plans published | 1 | 1 |
| Spec score · Monorepo Management Tools | 8.8 (#1) | 8.0 (#13) |
| Spec score · Build Automation Software | 8.8 (#3) | 8.1 (#12) |
| Spec score · Game Build Automation Software | 8.7 (#7) | 8.0 (#21) |
| Languages | Bazel supports languages including C++, Java, Kotlin, Python, Go, and Rust. | The language support table lists C/C++, Erlang, Go, Haskell, Java, Kotlin, OCaml, Python, and Rust with available prelude rules; support usability varies by language. |
| Maker | Google identifies Bazel as its own build tool. | Buck2 is a build system from Meta and the repository says it was designed by Meta. |
| Purpose | Bazel is an open-source tool that automates software builds and tests. | Buck2 is a large-scale, fast, hermetic, multi-language build system and the successor to Buck. |
| Support | The project directs users to its discussion group, GitHub issue tracker, Slack, and Stack Overflow. | The project directs users to report issues through GitHub and provides a community Discord server. |
Plans
In their own words
Bazel
Bazel is a free, open-source tool for automating software builds and tests across languages and platforms. Projects define targets in BUILD files using Starlark, which can also be used to create custom rules and macros. Bazel caches prior work and rebuilds what needs to change, while running tasks in parallel. It supports languages including C++, Java, Kotlin, Python, Go, and Rust, with outputs for desktop, server, Android, and iOS. Bazel runs on Linux, macOS, and Windows, and the documentation describes builds with 100,000 or more source files across multiple repositories. Sandboxing can make builds and tests more hermetic, and failures return a non-zero exit code for basic CI integration. Teams can share outputs through a remote cache, but must select and maintain its backend and secure access because it can contain binaries. IDE options include plugins for IntelliJ, Android Studio, CLion, and Visual Studio Code, plus Xcode integration. Bazel is not well suited to uncached deployment steps that change cloud configuration.
Buck2
Buck2 is a free build system from Meta for large-scale repositories that combine multiple programming languages. It uses Starlark rules, a dynamic dependency graph, and incremental actions to support extensible builds. Its language table lists prelude rules for C/C++, Erlang, Go, Haskell, Java, Kotlin, OCaml, Python, and Rust, though usability varies by language. Build actions can run remotely through services exposing Bazel's remote execution API; the project lists BuildBarn, BuildBuddy, EngFlow, and NativeLink as compatible with its distributed compilation support. Buck2 supports filesystem watching and can integrate with Meta's optional Eden virtual filesystem. Rules are hermetic by default and missing dependencies are errors, but local-only build steps are not sandboxed. The project describes Buck2 as early-stage and says it has no stable release tag; its latest binary tag changes with repository pushes. It warns that outside users may encounter rough edges, missing features, and missing toolchains. Source and binaries are available under MIT and Apache-2.0 licenses. The project directs users to GitHub for issue reports and offers a community Discord server.