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 hiring a research engineer focused on developer experience to build Tinker while using Tinker — working hands-on with real users and turning their challenges into product improvements. You’ll write and update cookbook recipes, add library features, prototype integrations, and ensure users can customize models smoothly. This role is a bridge between Tinker users and our research and infrastructure teams. You’ll surface user patterns to guide product and infrastructure priorities, and share what you learn through blog posts, demos, and code examples. This is a technical-first role with a major user-facing component. It’s ideal for someone who’s happiest in a code editor or Jupyter notebook, but who also enjoys talking to creative people. Tinker is flexible by design to empower novel and ambitious use cases for model fine-tuning — your job is to help them succeed. What You’ll Do • Write, test, and maintain high-quality code examples, recipes, and documentation in the Tinker cookbook. • Work directly with a variety of users to debug technical issues and optimize their fine-tuning pipelines. • Partner with internal research and infra teams to identify and prioritize improvements to Tinker’s developer experience. • Build tools, integrations, and demos that reduce user friction and make it easy to experiment and deploy models. • Share insights from the field through posts, guides, and talks. • Help develop Tinker’s near-term roadmap and long-term product strategy. Preferred Qualifications Enabling user success in building on top of an advanced platform is a skill that can be developed through many paths. You might demonstrate that you have it if you: • Experienced with fine-tuning large language models (LLMs) with supervised and reinforcement learning, and how to tune the hyperparameters of these algorithms. • Experienced with developing software libraries, especially open-source libraries. • Are thoughtful about developer experience, with clear ideas around developer ergonomics, onboarding flow, and sharp edges. • Are passionate about engaging with open-source communities, whether by contributing code, answering questions, or sharing learnings. • Have written public or internal code examples, tutorials, or papers that helped others understand and apply technical concepts. • Are comfortable reasoning about model training, fine-tuning, and inference, and can credibly discuss tradeoffs between different approaches. Logistics • Location: This role is based in San Francisco, California. • 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 applicable state or local fair chance ordinance or law.