source: Simon Willison: Mojo🔥 is now open source
level: technical
Mojo, a programming language designed for GPU programming with Python-like syntax, has released its compiler and toolchain under the Apache 2 license. The language first promised an open source release in May 2023, and after shipping version 1.0 last week, it has now fulfilled that commitment. Mojo aims to make GPU programming easier while drawing inspiration from Python, though it is not fully compatible with existing Python code.
The open source release includes the compiler and toolchain, allowing developers to use and modify Mojo freely. The language's original goal was to be a superset of Python, but that plan changed in August 2025. Mojo now focuses on being its own language optimized for GPU programming, with syntax inspired by Python. The project acknowledges that AI-assisted coding tools can help migrate Python code to Mojo, but full compatibility is not guaranteed.
Mojo's open source release is significant for developers working on GPU-intensive applications, as it provides a new tool for high-performance computing. The language's Python-inspired syntax may lower the barrier to entry for those familiar with Python. However, the shift away from being a Python superset means existing Python code may require modification. The release under Apache 2 license allows for broad use and contribution, potentially accelerating Mojo's development and adoption.
why it matters: Open sourcing Mojo lets AI and data science teams use and extend a Python-like language for GPU programming without licensing restrictions.