The Mojo Language Goes Fully Open Under the Apache 2.0 License

Modular has announced that its Mojo programming language is now fully open. The source code of the compiler, the toolchain and everything needed to build the language is now available in the company's GitHub repository under the Apache 2.0 license with LLVM exceptions.

Mojo is billed as an ambitious bet: a general-purpose language that absorbs the latest advances in compilers and language design and is built to work with GPUs, AI accelerators and other modern computing platforms. Over the past four years the language has been developed with the participation of an open community, but with a closed compiler. Last week Mojo reached version 1.0 with source-code stability, and now Modular has opened up the entire compiler and toolchain.

Why Apache 2.0

Modular explains its choice of license by pointing out that Apache 2.0 is considered the gold standard for languages and compilers: it grants broad freedom of use across a wide variety of scenarios, while the LLVM extensions further simplify building and distributing the binaries produced from Mojo code.

The opening up happened in stages and deliberately. According to the company, the “soul” of a language is best found by small, tight-knit teams rather than committees, yet feedback from the broader community is essential to avoid getting trapped in one's own echo chamber. First the standard library was opened, then hundreds of thousands of lines of kernel code written in Mojo, along with tools and supporting components, were published, and only now has the compiler's turn come.

How to build it

All of the code is available in Modular's main repository on GitHub. To build the compiler from source and run it on a Mojo file, it is enough to clone the repository and run a single command through the Bazel build system, which Modular uses to manage complex compilation and caching processes. Those who are not working on the compiler itself have access to a flag that downloads a prebuilt nightly build, which saves time.

That said, Modular is not yet ready to accept third-party contributions to the compiler and toolchain code — unlike the standard library, where changes have been accepted since 2024. The company attributes its caution to the need to work out a careful approach to contributions, especially in an era of writing code with the help of AI, and it expects to open up the compiler to changes before the end of this year.

The context is also worth noting: as Modular's own materials indicate, in July 2026 the company was acquired by Qualcomm.

Source: Lobsters