Distcc: A fast, free distributed C/C++ compiler
25+ years ago, our company used Clearcase for version control and it's clearmake had distributed build capability. Clearcase used a multi version file system (MVFS) and had build auditing so clearmake knew exactly what versions of source files were used in each build step. It could distribute build requests to any machine that could render the same "view" of the FS.<p>Even without distributed builds, clearmake could re-use .o files built by other people if the input dependencies were identical. On a large multi-person project this meant that you would typically only need to build a very small percentage of the code base and the rest would be "winked in".<p>If you wanted to force a full build, you could farm it out across a dozen machines and get circa 10x speedup.<p>Clearcase lost the edge with the arrival of cheaper disk and multi-core CPUs. I'd say set the gold standard for version control and dependency tracking and nothing today comes close to it.