Software Engineer, Full Stack, Tinker

Thinking Machines Lab's mission is to empower humanity through advancing collaborative general intelligence. We're building a future where everyone has access to the knowledge and tools to make AI work for their unique needs and goals. We are scientists, engineers, and builders who’ve created some of the most widely used AI products, including ChatGPT and Character.ai, open-weights models like Mistral, as well as popular open source projects like PyTorch, OpenAI Gym, Fairseq, and Segment Anything. About Tinker Tinker is our fine-tuning API that empowers researchers and developers to customize frontier AI to their needs — opening access to capabilities that have previously been concentrated in a handful of labs. We manage the infrastructure while allowing Tinkerers full flexibility in training open weights models with their own data, algorithms, and for their own needs. Tinker is rapidly adding new customers, features, and novel use-cases. We’re hiring to grow the platform alongside the Tinker community. About the Role We're looking for a full stack engineer to build and ship the products and services that Tinker users interact with every day. You'll work across frontend, backend, and infrastructure building the Tinker console, developer tools, and whatever Tinker needs most. What You’ll Do Build and extend Tinker's APIs and backend services in Python and Rust, from job submission and orchestration to billing and usage tracking. Ship user-facing product surfaces — console and future tools — with React and TypeScript. Improve the developer experience for Tinker users: SDK ergonomics, error messages, API design, onboarding flow. Improve system reliability, observability, and security across Tinker's production environment; participate in on-call. Build internal tooling that accelerates the Tinker research and infrastructure teams. Skills and Qualifications Minimum qualifications: Bachelor's degree or equivalent experience in computer science, engineering, or similar. Proficiency in at least one backend language (we use Python and Rust). Some familiarity with React, TypeScript, or mobile platforms. Thrive in a highly collaborative environment involving many, different cross-functional partners and subject matter experts. A bias for action with a mindset to take initiative to work across different stacks and different teams where you spot the opportunity to make sure something ships. Preferred qualifications — we encourage you to apply if you meet some but not all of these: 4+ years building backend systems in production. Experience designing and maintaining backend APIs at scale, especially for developer-facing platforms. Experience building tooling or products for ML training, fine-tuning, or inference workloads. Familiarity with distributed training infrastructure, job orchestration, and GPU scheduling. Ability to build high-quality, production-level UIs from prototype to polish. Experience with developer experience work — SDK design, CLI tooling, API ergonomics, documentation. Logistics Location: This role is based in San Francisco, California or New York, New York. Compensation: Depending on background, skills and experience, the expected annual salary range for this position is $350,000 - $475,000 USD. Visa sponsorship: We sponsor visas. While we can't guarantee success for every candidate or role, if you're the right fit, we're committed to working through the visa process together. Benefits: Thinking Machines offers generous health, dental, and vision benefits, unlimited PTO, paid parental leave, and relocation support as needed. As set forth in Thinking Machines' Equal Employment Opportunity policy, we do not discriminate on the basis of any protected group status under any applicable law. Thinking Machines Lab will consider for employment qualified applicants with criminal histories in a manner consistent with the requirements of the California Fair Chance Act, the San Francisco Fair Chance Ordinance, and any other applic