Reflection AI · 7 hours ago
Member of Technical Staff - Open Source Lead
San Francisco, CA
Full-time
Onsite
Mid, Senior LevelReflection AI is on a mission to build open superintelligence and make it accessible to all. They are seeking a Lead Open Source Engineer to own the development of their open post-training and inference ecosystem, drive adoption of models, and engage with the open-source community.
Computer Software
Responsibilities
Own the development of Reflection’s open post-training and inference and deployment ecosystem, creating the standard for how the community customizes and interacts with our models
Build the RL and SFT tooling that external developers use to customize, fine-tune, and align models for their specific need, as well as taking the lead on inference and deployment
Extend or integrate with existing best-in-class frameworks (e.g., VeRL, torchtune, Tunix, vLLM, SGLang) to meet developers where they are
Create Reflection-native libraries when required for performance or flexibility, ensuring our open-weight users have a clean, powerful, production-grade toolkit
Drive the adoption of our models by reducing friction in the fine-tuning process, ensuring adaptation is safe, efficient, and scalable
Engage deeply with the open-source community to incorporate feedback and guide the roadmap of our external-facing tools
Qualification
Required
Graduate degree (MS or PhD) in Computer Science, Machine Learning, or related discipline, or equivalent practical experience in open source software
Strong portfolio of open source contributions, particularly in the LLM tooling space
Deep understanding of post-training techniques (SFT, RLHF, DPO) and the engineering challenges of applying them to large models
Solid software engineering capabilities with experience designing library APIs that are intuitive and robust
Proficient in Python and deep learning frameworks (PyTorch preferred)
Thrive in a fast-paced, high-agency startup environment with bias toward action
Passionate about advancing the frontier of intelligence
Benefits
Comprehensive medical, dental, vision, life, and disability insurance.
Fully paid parental leave for all new parents, including adoptive and surrogate journeys.
Financial support for family planning.
Paid time off when you need it, relocation support, and more perks that optimize your time.
Lunch and dinner are provided daily.
Regular off-sites and team celebrations.
Company
Reflection AI
Frontier open intelligence accessible to all. Our team previously built frontier LLMs at labs like DeepMind, OpenAI, and Anthropic.
11-50 employees
H1B Sponsorship
Reflection AI has a track record of offering H1B sponsorships. Please note that this does not
guarantee sponsorship for this specific role. Below presents additional info for your
reference. (Data Powered by US Department of Labor)
Distribution of Different Job Fields Receiving Sponsorship
Represents job field similar to this job
Trends of Total Sponsorships
2025 (5)
Funding
Current Stage
Early StageCompany data provided by crunchbase