ML Engineer, Post-Training and Evaluation

Job description

Our Mission Reflection’s mission is to build open superintelligence and make it accessible to all . We’re developing open weight models for individuals, agents, enterprises, and even nation states. Our team of AI researchers and company builders come from DeepMind, OpenAI, Google Brain, Meta, Character.AI, Anthropic and beyond. Role Overview: We're looking for a core member of Reflection's Applied AI team to drive model fine-tuning and evaluations for enterprise customers. This team takes Reflection's open-weight models and adapts them for specific customer domains, tasks, and constraints. As a ML Engineer, you will work hands-on with customer data, run fine-tuning workflows, build evaluation harnesses, and deploy adapted models to production. You'll work directly with customers to understand what they need and with research teams to push what's possible. What You'll Do: Fine-tune Reflection's open-weight models for customer-specific use cases: prepare datasets, configure training runs (SFT, preference optimization, reinforcement fine-tuning), and iterate based on evals. Build and maintain evaluation infrastructure: design eval suites, curate test sets, establish baselines, and mea...