Research Engineer

Job Summary
:

Mercor is at the intersection of labor markets and AI research, partnering with leading AI labs to provide essential human intelligence for AI development. As a Research Engineer, you will work on engineering and applied AI research to enhance frontier language models through various experimental and data generation workflows.

Responsibilities
:

• 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.

Qualifications
:
Required
:

• 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/No

SQL 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.

Preferred
:

• 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.

Company
:

Mercor is an AI-based hiring platform that improves the recruitment process by matching talent with opportunities tailored to their skills. Founded in 2023, the company is headquartered in San Francisco, USA, with a team of 51-200 employees. The company is currently Growth Stage.