Bazel vs FASTBuild
Bazel
bazel.build
FASTBuild
fastbuild.orgSide by side
| Figure | Bazel | FASTBuild |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| Plans published | 1 | 1 |
| Spec score · Build Automation Software | 8.8 (#3) | 8.6 (#6) |
| Spec score · Game Build Automation Software | 8.7 (#7) | 8.4 (#15) |
| Caching | Teams and continuous integration systems can share build outputs through a remote cache, which requires a separately chosen and maintained backend server. | Compilation results can be shared between builds using a local or network cache. |
| Purpose | Bazel is an open-source tool that automates software builds and tests. | FASTBuild is an open-source build system for scalable compilation, caching, and network distribution. |
| Support | The project directs users to its discussion group, GitHub issue tracker, Slack, and Stack Overflow. | The site directs bug reports, feature requests and questions to GitHub issues and provides online or downloadable documentation. |
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.
FASTBuild
FASTBuild is an open-source build system for compiling software across Linux, macOS and Windows. It runs compilation work across worker threads, can reuse results from local or network caches, and can distribute builds among networked machines when their settings and worker setup are compatible. The maker says caching can accelerate compile times up to 10x. Some compiler settings do not support caching or distribution; FASTBuild handles affected objects without caching or builds them locally. Supported toolchains include MSVC, GCC, SNC, Clang, GreenHills, CodeWarrior and NVCC, plus syntactically compatible command-line compilers. It can combine C++ files into Unity or Blob builds, while allowing writable files to be built individually for quicker iteration. FASTBuild can generate Visual Studio and XCode project files. The maker describes it as a self-contained executable that needs no installation or dependencies beyond compiler tools. It is free, with commercial use and redistribution allowed under license conditions; the license provides the software without warranty. The listed current release is v1.20, released 26-Apr-2026.