I am working on Grog, the “grug-brained” alternative to Bazel. A mono-repo build tool where all you do is provide your build commands and interdependencies and the tool will run everything in parallel while caching as much as possible.
If you are a small to mid-sized team, moving to Bazel is massively painful and basically requires up to one full-time position to provide your team with a good experience.
Grog on the other hand let's you keep your existing build setup while just parallelizing and caching it. It's not a full replacement, but it's more than enough for most mid-sized teams that want to have fast mono-repo builds.