Act vs Bazel

act is an open-source command-line tool that runs GitHub Actions workflows locally using Docker containers. It reads workflow files from .github/workflows/ and executes them with environment variables and filesystem configurations matching GitHub's hosted runners. The tool enables fast local feedback on workflow changes without requiring commits and pushes to a remote repository.

Bazel is an open-source build and test tool developed by Google that supports multi-language, multi-platform projects at scale. It uses a declarative build language (Starlark) and features reproducible builds with remote caching and execution.