FASTBuild

FASTBuild is a free, open-source build system for developers and studios compiling sizeable C++ projects across local and networked machines. It is best for teams with compatible compiler configurations that want parallel work, reusable build results and optional remote capacity. The main trade-off is that incompatible settings force some work back to local, uncached compilation.

Overview

FASTBuild targets Windows, Linux and macOS (OS X) and is used by independent developers and large studios making software for PCs, Macs, Linux, consoles, smartphones and retro systems. It is a particularly relevant option for game and systems-development teams, but its build-system role is broader than games.

The program is a small, self-contained executable: there is no installation step or external dependency beyond the compiler tools themselves. Version 1.20 is identified as the current release, dated 26-Apr-2026. Its license allows commercial use, modification and redistribution subject to the license conditions, while providing the software without an express or implied warranty.

Key features

Parallel compilation, caching and distribution

Compilation tasks run across worker threads, using available CPU cores instead of serially processing the whole build. That makes FASTBuild a sensible choice for multicore development machines and large source trees. A built-in cache stores compilation results locally or on a network, so unchanged work can be reused in later builds; the maker says caching can accelerate compile times by up to 10x.

Network distribution lets other machines contribute workers, potentially adding considerably more capacity than one workstation. It is not automatic magic: worker discovery and startup, compiler synchronization and compatible settings all matter. FASTBuild detects settings that cannot be distributed and builds those objects locally, so mixed workloads may gain less than their fully compatible portions.

Targets and toolchains

Listed targets include Windows, OS X, Linux, iOS, Android and major game consoles. Supported toolchains include MSVC, GCC, SNC, Clang, GreenHills, CodeWarrior and NVCC for CUDA, plus command-line compilers with compatible syntax. This breadth favors studios maintaining several platform outputs, provided each toolchain is configured consistently enough for caching and distribution.

Unity builds and IDE workflow

FASTBuild can create Unity or Blob builds by combining multiple C++ files. Writable files can still be built individually, which preserves a quicker iteration path when editing selected sources rather than rebuilding every combined unit. It can generate Visual Studio and XCode project files, and its output is Visual Studio compatible, allowing teams to retain familiar IDE workflows while using FASTBuild for compilation.

Extensions and support

The downloads page lists third-party Unreal Engine integrations, build visualizers and editor support for Emacs, Sublime, Vim and VSCode, along with Visual Studio and VSCode-related tooling. Bug reports, feature requests and questions go through GitHub issues, with online and downloadable documentation for setup and use.

Pricing

There is no paid tier, seat charge, trial period or renewal commitment. The free release includes build-as-code, build caching and remote execution across a multi-platform tool. In return, users take responsibility for configuring workers and compilers, and the warranty disclaimer applies.

Platforms

FASTBuild runs on Linux, macOS and Windows. Its build targets extend to Windows, OS X, Linux, iOS, Android and major game consoles, subject to the relevant compiler and platform setup.

Who it's for

Choose FASTBuild if you are an independent developer or studio with large C++ builds, multiple CPU cores, spare network machines or a need to share compilation results between developers and builds. It is especially compelling for cross-platform and game projects using one of its supported toolchains. It is less suitable when compiler settings routinely prevent caching or distribution, or when a team wants a managed service rather than self-configured open-source infrastructure.

Pros and cons

Pros

• No purchase barrier: the open-source release costs 0.00 USD and permits commercial use and redistribution under its license.
• Several acceleration paths: local parallelism, local or network caching and remote workers can be combined for demanding builds.
• Broad development reach: support spans desktop, mobile and console targets and a long list of compiler families.
• Lightweight deployment: a self-contained executable avoids an installation framework or non-compiler dependencies.
• IDE continuity: generated Visual Studio and XCode projects and Visual Studio-compatible output reduce disruption to existing workflows.

Cons

• Configuration-sensitive distribution: incompatible compiler settings require local builds, reducing the benefit of network workers.
• Cache exclusions: some settings also bypass caching, so repeated builds may not see the advertised acceleration.
• Operational responsibility: worker discovery, startup and compiler synchronization must be arranged correctly by the team.
• No warranty: the license supplies the software as-is, leaving deployment risk with the user.

Alternatives

Bazel is another free, open-source build and test tool for Linux, macOS and Windows, and is the better comparison for teams seeking a general build-and-test system from Google.

Nx suits teams wanting a freemium workflow with a free Hobby plan, 50,000 monthly credits, five contributors and 10 concurrent CI connections rather than a purely self-managed executable.

fastlane is free open source across Android, iOS, Linux, macOS and Windows and is the alternative to consider when the priority is mobile delivery automation.

Qbs offers a free build-system option across desktop and mobile platforms under commercial, LGPL 3 or GPL 2 licensing.

SCons is a free MIT-licensed choice for Linux, macOS, Windows and self-hosted environments.

Apache Ant is a free Java-based option requiring Java 8 or later. Apache Maven is the free Apache-licensed alternative for Java projects and requires a JDK 8 or newer for Maven 3.10. Buck2 is Meta-designed open-source build tooling for teams evaluating that ecosystem.

Verdict

FASTBuild is a strong recommendation for developers and studios with substantial, compatible C++ builds: it combines zero licensing cost with parallel compilation, reusable caches and optional network scale. Look elsewhere if your compiler settings frequently block those features or if you prefer a build service with less worker and toolchain configuration to own.