Bazel vs Blaze

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.

Blaze is a build system aimed mainly at monorepos, with general task running and productivity tooling as other uses. It runs multiple tasks across a repository and manages dependencies between projects, supporting parallel execution and a configurable local cache for completed work. Configuration options include JSON, YAML, and Jsonnet, with advanced templating. A plugin system runs tasks through executors. Blaze says it supports any language or framework without affecting application code, and teams can keep integration and deployment processes in the monorepo for reuse. It does not manage application dependencies, analyze code, or track project technologies. Linux, macOS, and Windows are listed as supported platforms, with prebuilt binaries for common platforms. The project is still under development, and its site invites help stabilizing it ahead of an alpha release. The Free plan costs nothing. Documentation directs users to GitHub Issues for problems and bugs, and the site links to a Discord community.