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Mojo open-sources compiler and toolchain under Apache 2

toolsThe Glonce editorsSimon Willison🔥66Glonce rating66Impact65Novelty60Relevance85Surprise45Players55Credibility75

On 18 August 2026, the Mojo programming language's compiler and toolchain were released as open source under an Apache 2 license, a week after Mojo shipped its 1.0 release. The move fulfills a promise the project made in May 2023, when it first said an open-source release was coming.

Mojo's original goal at launch was to become a full superset of Python, so that existing Python code could be used to bootstrap its ecosystem. That plan changed around August 2025: the project said Mojo may or may not evolve into a full Python superset, and that it's fine if it doesn't, adding that it's encouraged by how well AI-assisted coding tools already help migrate Python code to Mojo and expects future tooling and ecosystem maturity to smooth that evolution further. As a result, Mojo is now presented as its own language, built to make GPU programming as painless as possible, with syntax inspired by Python but not 100% compatible with existing Python code.

Key facts

  • Mojo's compiler and toolchain were released under an Apache 2 license on 18 August 2026, fulfilling a promise made since May 2023.
  • The open-source release follows Mojo's 1.0 release the week before.
  • Mojo originally aimed to be a full superset of Python so existing Python code could bootstrap its ecosystem; that goal changed around August 2025.
  • Mojo is now described as its own language, with syntax inspired by Python but not 100% compatible with existing Python code, built to make GPU programming easier.
  • The project says it is encouraged by how well AI-assisted coding tools already help migrate Python code to Mojo, and expects future tooling to smooth that path further.

Why it matters

The Mojo programming language's compiler and toolchain went open source under an Apache 2 license, closing out a promise the project made in May 2023, one week after Mojo reached its 1.0 release. The move also confirms a shift in direction: Mojo no longer aims to be a full superset of Python, the goal it launched with.

Who it affects

Developers building GPU-heavy or performance-critical code, particularly Python programmers looking for a faster path into GPU programming, plus anyone who wants to inspect, modify or redistribute the compiler and toolchain under the permissive Apache 2 terms.

How to use it

The compiler and toolchain are available under the Apache 2 license, which permits use, modification and redistribution, including in proprietary projects. The source gives no pricing or tiering details, only the licensing terms of the open-source release itself.

How solid is it

The information comes from Simon Willison's link blog, dated 18 August 2026, which quotes the Mojo project's own statement about its shifted ambitions and adds his own read on where the language stands today. No company name or spokesperson is given in the source.

Risks and caveats

Mojo's syntax is inspired by Python but is not 100% compatible with existing Python code, so it is not a drop-in replacement or an automatic migration path. The source gives no specific release date beyond "last week" and "today," and does not detail what has changed in the AI-assisted coding tools it credits with easing Python-to-Mojo migration.

“Today Mojo is its own language, optimized to make GPU programming as painless as possible using syntax inspired by Python, if not 100% compatible with existing code.”

— Simon Willison