Modular fully open-sources the Mojo compiler

Mojo just went fully open source.

Modular released the source code for the Mojo compiler and toolchain under an Apache 2.0 license with LLVM exceptions. The move comes right after the high-performance language hit version 1.0. After four years of public development with a closed core, the entire toolchain is now available in Modular's main GitHub repository.

Why it matters: Mojo was built to give developers Python-style syntax that runs directly on GPUs and hardware accelerators. Opening the compiler gives AI systems engineers total visibility into the underlying tech stack—and means you no longer have to rely on a black-box binary to use it.

Here's the gist on trying it: clone github.com/modular/modular and run ./bazelw run --config=build-mojo KGEN:mojo -- run hello.mojo. Modular currently accepts contributions for the Mojo standard library, but compiler code pull requests won't open until later this year.

The AI-focused language finally dropped its closed hood.