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 is building the future of systems programming for the AI era. Our language, compiler, runtime, and SDK enable developers to build portable, high-performance software that runs seamlessly across CPUs, GPUs, and next-generation AI accelerators.
As a Principal Compiler Engineer, you'll provide technical leadership for the Mojo compiler backend while helping shape the long-term direction of the language and developer experience. This is an individual contributor leadership role, where you'll partner closely with the Compiler Engineering Manager to define architecture, drive technical strategy, mentor engineers, and deliver compiler innovations that power the next generation of AI software.
While your primary focus will be the compiler backend—from MLIR lowering through LLVM and custom code generation—you'll also play a key role in advancing Mojo's developer tooling ecosystem, including debugging, profiling, and language tooling. You'll help grow the team's technical capabilities while influencing the broader direction of the Mojo platform.
LOCATION: Candidates based in the US, Canada, and Edinburgh are welcome to apply. To support growth and collaboration, those in earlier career stages work in a hybrid capacity at our Los Altos, CA or Edinburgh office (minimum two days per week on-site), with relocation assistance available for eligible candidates. Senior engineers have both remote and in-office flexibility. All new hires complete onboarding in person.

What you will do:

• Own the technical vision and architecture for the Mojo compiler backend, driving IR lowering, optimization passes, and code generation across CPUs, GPUs, and emerging AI accelerators.
• Lead complex compiler initiatives spanning MLIR, LLVM, and custom backend technologies while defining scalable architectures for future hardware targets.
• Serve as the technical leader for backend compiler engineering by driving design reviews, establishing engineering standards, mentoring teammates, and raising the overall technical bar.
• Design and implement compiler optimizations informed by real-world performance analysis, profiling data, and workload characteristics.
• Lead the evolution of Mojo's debugging and developer tooling ecosystem, including LLDB integration, profiling, debug information, language tooling, and next-generation developer workflows.
• Partner closely with engineers across the Mojo language, MAX, kernel, runtime, hardware enablement, and AI infrastructure teams to deliver a unified compiler platform.
• Collaborate with Developer Relations and the open-source community to gather feedback, shape technical direction, and support external contributors.
• Mentor engineers across the compiler organization, helping them grow technically while fostering a culture of technical excellence and continuous learning.

What you bring to the table:

Required

• Deep hands-on experience building production compilers, including IR design, optimization passes, lowering pipelines, and code generation.
• Strong expertise with both LLVM and MLIR, including dialect development, conversion pipelines, optimization infrastructure, and backend code generation.
• Demonstrated technical leadership as a senior individual contributor, driving architecture, influencing technical direction, and mentoring engineers without formal management responsibilities.
• Expert-level C++ and strong Python proficiency.
• Experience building or extending debugger infrastructure, particularly within the LLDB or GDB ecosystem.
• Experience developing language tooling, such as language servers (LSP), IDE integrations, or other developer productivity tools.
• Strong understanding of modern CPU and GPU architectures, compiler performance optimization, and systems-level programming.
• Excellent communication skills with a proven ability to collaborate across distributed engineering teams.

Strongly Preferred

• Experience contributing to open-source compiler projects or developer-facing SDKs.
• Experience partnering directly with users and developer communities to influence product direction.
• Expertise with profiling and performance analysis tools such as Linux perf, LLVM XRay, VTune, or equivalent.

What qualities will make you successful

• You enjoy solving deeply technical problems while helping other engineers succeed.
• You thrive in ambiguous environments and are comfortable defining technical direction where no roadmap yet exists.
• You balance long-term architectural thinking with pragmatic execution.
• You're passionate about building world-class developer tools and exceptional programming languages.
• You naturally mentor others, elevate engineering quality, and create clarity around complex technical decisions.
• You enjoy collaborating across compiler, runtime, AI infrastructure, and hardware teams to solve end-to-end systems challenges.

What you can expect

• Technical ownership over some of the most critical components of the Mojo compiler and developer tooling ecosystem.
• The opportunity to shape how developers build software for the next generation of AI hardware.
• Collaboration with world-class engineers across compilers, AI infrastructure, systems programming, and hardware acceleration.
• Significant influence over technical strategy, architecture, and the long-term evolution of the Mojo compiler.
• The opportunity to contribute extensively to open source and build technology used by developers around the world.
• A fast-moving, engineering-first environment where curiosity, ownership, and technical excellence drive everything we build.

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 $261,000.00 - $319,000.00 USD. 
The estimated base salary range for this role to be performed in Canada, regardless of the province, is $256,000.00 - $313,000.00 CAD.
The estimated base salary range for this role to be performed in the United Kingdom is £151,000.00 - £185,000.00 GBP. 
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. 

Modular is proud to emphasize an equal opportunity, safe environment for people to do their best work. Modular is an affirmative action employer. We are committed to providing equal employment opportunities regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability, gender identity, or Veteran status. We also consider qualified applicants regardless of criminal histories, consistent with legal requirements.

If you require reasonable accommodations to participate in the interview process, please let your recruiter know, and we will work with you to meet your needs in compliance with the ADA.

This employer participates in E-Verify and will provide the federal government with your Form I-9 information to confirm that you are authorized to work in the U.S. If E-Verify cannot confirm that you are authorized to work, this employer is required to give you written instructions and an opportunity to contact Department of Homeland Security (DHS) or Social Security Administration (SSA) so you can begin to resolve the issue before the employer can take any action against you, including terminating your employment. Employers can only use E-Verify once you have accepted a job offer and completed the Form I-9.

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