Buck2 vs Qbs

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.

Qbs is a build automation tool for managing software projects across multiple platforms. Projects can use it regardless of programming language, toolkit, or libraries, and its declarative model lets them describe build tasks and dependencies without setting the build order. The manual lists correct, fast incremental builds and an extensible architecture among its features. Qbs documents built-in support for Windows, Linux, macOS, Android, iOS, tvOS, watchOS, QNX, and FreeBSD, plus cross-compilation. It can be used with Qt Creator and Visual Studio Code through the Qbs session feature, and it can generate Clang compilation databases. Project generation for Visual Studio, IAR Embedded Workbench, and Keil uVision is available but described as experimental. Binaries are available for Windows, macOS, Linux, and FreeBSD, or Qbs can be built locally from source. The Qbs plan costs nothing. Its library and tools are available under commercial licenses, LGPL version 3, and GPL version 2. The Makefile generator will not create a Makefile if the source, build, or install root directory contains spaces; other UNIX-like systems may work but are not regularly tested or officially supported.