Mojo Libraries Engineer

About the role:

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.
LOCATION: Candidates based in the US or Canada are welcome to apply. You can work in our office in Los Altos, CA or remotely from home. Onboarding for new hires is conducted in-person in our Los Altos, CA office.

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.

 

What Modular brings to the table:

• Amazing Team. We are a progressive and agile team with some of the industry’s best engineering and product leaders.
• World-class Benefits. In order to attract the best, we need to offer the best. Premier insurance plans, up to 5% 401k matching, flexible paid time off, and more are available to you! Please note that specific benefit packages may vary based on your location.
• Competitive Compensation. We offer very strong compensation packages, including stock options. We want people to be focused on their best work and believe in tailoring compensation plans to meet the needs of our workforce. 
• Team Building Events. We organize regular team onsites and local meetups in Los Altos, CA as well as different cities. Traveling 2-4 times a year is expected for all roles. 

Working at Modular will enable you to grow quickly as you work alongside incredibly motivated and talented people who have high standards, possess a growth mindset, and a purpose to truly change the world. The estimated base salary range for this role to be performed in the US, regardless of the state, is $167,000.00 - $286,000.00 USD. The estimated base salary range for this role to be performed in Canada, regardless of the province, is $158,000.00 - $270,000.00 CAD.The salary for the successful applicant will depend on a variety of permissible, non-discriminatory job-related factors, which include but are not limited to education, training, work experience, business needs, or market demands. This range may be modified in the future. The total compensation for a candidate will also include annual target bonus, equity, and benefits, with equity making up a significant portion of your total compensation.
For candidates who fall outside of the listed requirements, we nevertheless encourage you to apply as we may have openings that are lower/higher level than the ones advertised.