Airbnb yanked tens of millions of lines of Java, Kotlin, and Scala out of Gradle and dropped them into Bazel. Why? Faster builds, reproducible results, and smoother dev workflows.

They didn’t just swap tools—they rewired the whole thing. A custom automated build file generator now slices up targets fine enough to multiply build granularity 10x. Toss in dependency inference, and parallelism shot way up.