AI Library Engineer

Location: United States

Department: MAX

Location Type: IN_OFFICE

Employment Type: FULL_TIME

About the role:

What you will do:

• Develop the API surface for MAX: namespaces, core abstractions, extension points, programming model, compatibility guarantees and developer experience.
• Develop and design inference APIs that support real-world serving needs: model loading, distributed inference, quantization, tokenization/pipelines, configuration surfaces, batching/streaming, and deployment-oriented ergonomics.
• Develop training APIs that scale from single device to distributed execution, with clear primitives for device placement, parallelism, checkpointing, and observability.
• Contribute to a coherent programming model across Python and Mojo-adjacent surfaces: align naming, types, and conventions; avoid leaky abstractions; define the "pit of success".
• Work on technical RFCs and technical specs: write and socialize proposals; gather feedback from internal model engineers and external users; iterate towards consensus.
• Partner cross-functionally with compiler/runtime, kernels, cloud/serving, and documentation/DevRel teams to ensure APIs map cleanly to underlying capabilities.
• Develop reference implementations and exemplar code: golden-path examples, architecture templates, and best-practice patterns that teams can copy.

What you bring to the table:

•  Passion for designing developer-facing APIs (SDKs, frameworks, or platforms).
• Good understanding of modern AI frameworks and their design tradeoffs (e.g., PyTorch, JAX, TensorFlow, vLLM, XLA/MLIR-adjacent ecosystems).
• Proficiency in one or more systems / performance languages (C++, Rust, Go) and one or more user-facing languages (Python; familiarity with Mojo is a plus).
• Good instincts and a passion for API ergonomics: naming, composability, types, error handling, configurability, and clarity.
• Strong written communication: you can write specs that engineers can implement without ambiguity.
• Passion for engineering standards, pragmatism, and a bias towards incremental development without compromising long term design.

Nice to have

• Prior experience in an AI framework or library.
• Prior experience in developer experience research.
• Prior experience designing programming languages and abstractions

What success looks like (first 3–6 months)

• Direct contribution to various API surfaces, grounded in concrete developer journeys.
• One or more high-impact developments (e.g., a simplified public namespace, clarified tiers such as low-level vs high-level APIs, improved config surfaces).
• Reference examples and docs that unblock internal model bring-up and external adoption

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.