Mojo Libraries Engineer

About Modular

At Modular, we’re on a mission to revolutionize AI infrastructure by systematically rebuilding the AI software stack from the ground up. Our team, made up of industry leaders and experts, is building cutting-edge, modular infrastructure that simplifies AI development and deployment. By rethinking the complexities of AI systems, we’re empowering everyone to unlock AI’s full potential and tackle some of the world’s most pressing challenges. If you’re passionate about shaping the future of AI and creating tools that make a real difference in people’s lives, we want you on our team. You can read about our culture and careers to understand how we work and what we value.

About The Role: Mojo Libraries Engineer

At Modular, we're on a mission to make AI accessible to everyone. As a Mojo Libraries Engineer, you'll help realize this vision by shaping the foundational libraries of the Mojo programming language. Mojo combines performance and expressiveness to unlock the full potential of modern hardware for AI. In this role, you'll design and implement core abstractions across the Mojo Standard Library and kernel libraries — empowering developers to build efficiently, integrate with AI systems, and accelerate innovation across the AI stack.

What You Will Do

• Partner with teams across Modular—including compiler, kernel, and runtime engineers—to design APIs that are ergonomic, expressive, and performance-conscious. Your work will directly shape the developer experience and deliver high business impact by enabling critical customer workloads and accelerating platform adoption.
• Design and implement abstractions that enable the development and optimization of kernels and algorithms running on GPUs and CPUs, delivering top-tier performance and accuracy throughout the GenAI inference solution stack.
• Optimize library functionality for performance, memory efficiency, and hardware utilization.
• Participate in design discussions and code reviews to uphold high engineering standards.
• Collaborate with other engineering teams to align the standard library with broader platform needs.
• Contribute to a fully open source project — everything you build will be public and part of our GitHub repo.
• Engage with the open source community to support high-quality contributions and foster a welcoming, inclusive environment.

What You Bring To The Table

• Experience with GPU programming languages like CUDA or OpenCL.
• Deep understanding of GPU architecture (memory hierarchies, tensor cores, etc.) and how it influences algorithm and API design.
• Proficiency in modern systems languages (C++, Rust, or Swift), with strong skills in low-level programming, performance optimization, and memory management.
• Passion for both library design and performance, with a commitment to following modern API patterns and language evolution in C++, Rust, and Swift ecosystems.
• Hands-on open source experience — either through meaningful contributions or by maintaining and reviewing community submissions.
• A collaborative mindset, intellectual curiosity, and drive to solve complex technical challenges as part of a high-performing team.
• Strong alignment with Modular's cultural values and enthusiasm for building a thoughtful, inclusive engineering culture.

Helpful, But Not Required

• Familiarity with GPU assembly languages such as PTX and SASS.
• Knowledge of cutting-edge APIs such as CUTLASS or Triton.
• Prior experience with Mojo, especially with accepted contributions to the Mojo Standard Library.
• Familiarity with LLVM, MLIR, or Python, particularly in systems or compiler-related contexts.
• An advanced degree in Computer Science or a related field.

Key skills/competency

• Mojo Programming Language
• GPU Architecture
• CUDA/OpenCL
• C++/Rust/Swift
• Performance Optimization
• Memory Management
• API Design
• Open Source Contribution
• Compiler Design
• AI Infrastructure