Ninja is yet another build system. It takes as input the interdependencies offiles (typically source code and output executables) and orchestratesbuilding them, quickly..Ninja joins a sea of other build systems. Its distinguishing goal is to befast. It is born from the Chromium browser project, which has over 30,000source files and whose other build systems can take ten seconds to startbuilding after changing one file. Ninja is under a second.