Bazel is an open-source build and test tool similar to Make, Maven, and Gradle. It uses a human-readable, high-level build language. Bazel supports projects in multiple languages and builds outputs for multiple platforms. Bazel supports large codebases across multiple repositories, and large numbers of users.
It also builds code repeatably & hermetically (interpreted languages excepted; at google python is built super hermetically where a python binary + environment is bundled with python script(s) into an executable; some companies like dropbox have copied this). You run build, and you get binaries for N kinds of systems (e.g x86_64, ARM). It builds a dependency graph of your code that you can query and results in cache-able builds (only rebuild the part you need). Since building dependencies in a tree can be massively parallelized, it also allows you to parallelize your builds well across machines (with some effort).
You use the one tool to compile C++, Java, Python, Go, Rust, etc.
