Staff Research Engineer - Frontier AI and Reinforcement Learning - International

Braintrust; United States; Hybrid; USD 30,000 - 42,000; Full time

Job summary

Braintrust is seeking a Staff Research Engineer to advance frontier AI and reinforcement learning initiatives. You will work across synthetic and agentic data, model understanding, and evaluation, building research-grade prototypes and scalable AI systems.

Expected project length is three months, with an immediate start. Availability of 40 hours per week, 8 hours per day and four hours of daily Pacific Time overlap is required. LinkedIn profile in resume is requested.

Qualifications

• 7+ years of research engineering experience in machine learning or frontier AI.
• PhD or Master’s in AI/ML/CS or exceptional equivalent research experience.
• Strong foundations in ML and designing experiments.
• Experience in synthetic or agentic data generation, RL, or AI evaluation.
• Strong Python programming and modern ML tooling.
• Scientific judgment with reproducible methods and data quality.
• Excellent written and verbal communication; cross-functional collaboration.
• Experience mentoring engineers or researchers and providing technical leadership.

Responsibilities

• Investigate frontier-model capabilities, limitations and training methods; formulate research questions.
• Build datasets, experiments, prototypes, tooling and evaluation frameworks; train and evaluate models.
• Analyze results with rigor; ensure reproducibility and evidence-based interpretation.
• Collaborate across Research, Engineering, Product and Operations to translate findings into systems.
• Communicate findings via technical reports, publications and peer review; provide mentorship.

Skills

Python programming

Cross-functional collaboration

Experiment design

ML frameworks & tooling

Education

PhD or Master’s in AI/ML/CS

Tools

TensorFlow

PyTorch

Job description

• Rate: $26/hr
• Hours: 40 hours / week
• Experience: 5 - 10 years
• Location: Bangladesh | Brazil + 7 more

Advance frontier AI through research and engineering across synthetic and agentic data, reinforcement learning, post-training, model understanding, benchmarks and evaluation. You will investigate high-impact questions, build research-grade prototypes and help turn validated findings into scalable AI systems.

WHAT YOU WILL DO

• Investigate frontier-model capabilities, limitations and training methods, formulate research questions and explore new approaches.
• Build research datasets, experiments, prototypes, tooling and evaluation frameworks. Train, test and evaluate models using modern ML tools.
• Analyze results with scientific rigor, data quality, reproducibility and evidence-based interpretation. Iterate from hypotheses to validated insights.
• Collaborate across Research, Engineering, Product and Operations to translate findings into practical systems.
• Communicate findings through technical reports, publications, open-source work and research forums where appropriate. Contribute through peer review, mentorship and technical leadership.

WHAT YOU WILL BRING

• 7+ years of professional experience with significant research engineering experience in machine learning or frontier AI systems.
• A PhD or master's degree in AI, machine learning, computer science or a closely related technical field, or exceptional equivalent research experience.
• Strong ML foundations and experience designing experiments, training or evaluating models, or developing AI systems.
• Research experience in at least one of synthetic or agentic data generation, reinforcement learning or post-training, model understanding, AI evaluation, benchmarks, or tool-using AI agents.
• Strong Python programming and experience implementing, testing and iterating with modern ML frameworks and tooling.
• Scientific judgment, rigorous reproducible methods and attention to data quality.
• Strong written and verbal communication, independent work and effective cross-functional collaboration.
• Experience mentoring engineers or researchers and providing technical leadership.

PROJECT DETAILS

Expected project length is three months, with an immediate start. Availability of at least 40 hours per week, 8 hours per day and four hours of daily Pacific Time overlap is required. Selection includes an approximately 20-minute client AI interview and a 45-60-minute technical delivery interview. Include your LinkedIn profile URL in your required resume.

Company: Staff Research Engineer - Frontier AI and Reinforcement Learning - International
Location: CIST