Research Engineer - Environments Data and Post-Training

Mercor is defining the future of work. We partner with leading AI labs and enterprises to provide the human intelligence essential to AI development.

Our vast talent network trains frontier AI models in the same way teachers teach students: by sharing knowledge experience and context that can't be captured in code alone. Today more than 30000 experts in our network collectively earn over $2 million a day.

Mercor is creating a new category of work where expertise powers AI advancement. Achieving this requires an ambitious fast-paced and deeply committed team. You’ll work alongside researchers operators and AI companies at the forefront of shaping the systems that are redefining society.

Mercor is a profitable Series C company valued at $10 billion. We work in-person five days a week in our San Francisco NYC or London offices.

As a Research Engineer at Mercor you’ll work at the intersection of engineering and applied AI research. You’ll contribute directly to post-training and RLVR synthetic data generation and large-scale evaluation workflows that meaningfully impact frontier language models.

Your work will be used to train large language models to master tool use agentic behavior and real-world reasoning in real-world production environments. You’ll shape rewards run post-training experiments and build scalable systems that improve model performance. You’ll help design and evaluate datasets create scalable data augmentation pipelines and build rubrics and evaluators that push the boundaries of what LLMs can learn.

• Work on post-training and RLVR pipelines to understand how datasets rewards and training strategies impact model performance.

• Design and run reward-shaping experiments and algorithmic improvements (e.g. GRPO DAPO) to improve LLM tool-use agentic behavior and real-world reasoning.

• Quantify data usability quality and performance uplift on key benchmarks.

• Build and maintain data generation and augmentation pipelines that scale with training needs.

• Create and refine rubrics evaluators and scoring frameworks that guide training and evaluation decisions.

• Build and operate LLM evaluation systems benchmarks and metrics at scale.

• Collaborate closely with AI researchers applied AI teams and experts producing training data.

• Operate in a fast-paced experimental research environment with rapid iteration cycles and high ownership.

• Strong applied research background with a focus on post-training and/or model evaluation.

• Strong coding proficiency and hands-on experience working with machine learning models.

• Strong understanding of data structures algorithms backend systems and core engineering fundamentals.

• Familiarity with APIs SQL/NoSQL databases and cloud platforms.

• Ability to reason deeply about model behavior experimental results and data quality.

• Excitement to work in person in San Francisco five days a week (with optional remote Saturdays) and thrive in a high-intensity high-ownership environment.

• Real-world post-training team experience in industry (highest priority).

• Publications at top-tier conferences (NeurIPS ICML ACL).

• Experience training models or evaluating model performance.

• Experience in synthetic data generation LLM evaluations or RL-style workflows.

• Work samples artifacts or code repositories demonstrating relevant skills.

• Generous equity grant vested over 4 years

• A $10K housing bonus (if you live within 0.5 miles of our office)

• A $1.5K monthly stipend for meals

• Free Equinox membership

• Health insurance

What We Do

We use AI to understand human ability and match talent with the opportunities they're best suited for.