STEM Research Jobs in Brazil at Rex.zone focus on applied engineering and research workflows that strengthen AI/ML training pipelines, including data labeling, RLHF evaluation, prompt evaluation, QA evaluation, named entity recognition, computer vision annotation, and content safety labeling. In this full-time remote role, you will collaborate with engineering and research stakeholders to improve training data quality, annotation guidelines compliance, and large language model evaluation so teams can drive model performance improvement from real-world signals. Explore Rex.zone to apply, compare remote, contract, freelance, and full-time options, and align your work with AI labs, tech startups, and annotation vendors supporting NLP, computer vision, and LLM training.
Keyword: STEM research jobs Brazil — STEM Research Engineer (Brazil) Date: 25-02-2026 Company: Rexzone Country: US Remote Type: Remote Employment Type: FULL_TIME Experience Level: Mid-Senior Industry: Technology Job Function: Engineering Skills: STEM research, experimental design, data analysis, Python, machine learning, statistical modeling, research documentation, literature review, reproducible research Salary Currency: USD Salary Min: 63360 Salary Max: 126720 Pay Period: YEAR
You will support STEM research initiatives that connect engineering experimentation with AI/ML data operations. Your work will translate research questions into measurable studies, create datasets and evaluation protocols, and contribute to LLM training pipelines through RLHF evaluation, prompt evaluation, and QA evaluation. You will partner with cross-functional teams to define annotation guidelines, validate training data quality, and identify error patterns that affect model performance improvement across NLP and computer vision use cases.
Design and run experiments that measure model behavior and data quality impacts. Build and analyze datasets for named entity recognition, content safety labeling, and model evaluation. Create clear annotation guidelines and ensure annotation guidelines compliance across contributors. Execute RLHF evaluation and prompt evaluation workflows; document rubrics and edge cases. Perform QA evaluation on labeled data and evaluations to reduce noise and bias. Collaborate with engineering teams to integrate findings into large language model evaluation and training iterations. Maintain reproducible research practices: versioning, documentation, and audit-ready artifacts. Track metrics tied to training data quality, evaluator agreement, and model performance improvement.
Mid-Senior experience in STEM research, engineering R&D, or applied research. Strong experimental design, statistical reasoning, and data analysis skills. Proficiency with Python and common data/science tooling. Ability to write research documentation that is clear, testable, and reproducible. Familiarity with machine learning fundamentals and evaluation methods. Comfort working in remote environments with cross-functional stakeholders.
Experience with LLM training pipelines, RLHF, or human evaluation programs. Exposure to data labeling operations, QA evaluation, or annotation vendor workflows. Hands-on work with NLP tasks (e.g., named entity recognition) and/or computer vision annotation. Experience with content safety labeling and policy-driven evaluations. Background working with AI labs, tech startups, BPOs, or annotation vendors supporting model development.
This is a Remote, FULL_TIME role with structured research milestones, written reviews, and metric-driven progress tracking. You will coordinate asynchronously, produce evaluation-ready datasets and reports, and support stakeholders who ship improvements into production model and data pipelines.
Salary Range: 63360–126720 USD per year, depending on skills and experience, aligned to engineering and research impact in AI/ML workflows.
Search Rex.zone for STEM research jobs Brazil and related remote roles across NLP, computer vision, content safety, and LLM training. You can also explore contract, freelance, entry-level, and senior variations to match your preferred scope and specialization.
Yes. Remote Type is Remote, and the role is designed for distributed research and engineering collaboration.
Yes. Employment Type is FULL_TIME.
It refers to a STEM research-focused engineering role aligned with Brazil as the target job search keyword and audience intent, emphasizing applied research workflows for AI/ML training pipelines and evaluation.
Common workflows include RLHF evaluation, prompt evaluation, QA evaluation, data labeling, named entity recognition, computer vision annotation, content safety labeling, and large language model evaluation tied to training data quality and model performance improvement.
The role supports Technology organizations and can align with AI labs, tech startups, BPOs, and annotation vendors working on NLP, computer vision, and LLM training.
Experience Level is Mid-Senior, with demonstrated capability in experimental design, data analysis, and research execution.
'%20stroke-width='1.1184'/%3e%3cline%20x1='13.9799'%20y1='14.5392'%20x2='13.9799'%20y2='0.000106738'%20stroke='url(%23paint1_linear_5108_6545)'%20stroke-width='1.1184'/%3e%3cline%20y1='-0.559198'%20x2='29.0783'%20y2='-0.559198'%20transform='matrix(-1%208.74228e-08%208.74228e-08%201%2029.0781%20136.539)'%20stroke='url(%23paint2_linear_5108_6545)'%20stroke-width='1.1184'/%3e%3cline%20y1='-0.559198'%20x2='14.5391'%20y2='-0.559198'%20transform='matrix(1.31134e-07%201%201%20-1.31134e-07%2014.5391%20122)'%20stroke='url(%23paint3_linear_5108_6545)'%20stroke-width='1.1184'/%3e%3cdefs%3e%3clinearGradient%20id='paint0_linear_5108_6545'%20x1='29.0781'%20y1='-0.499878'%20x2='-0.000152544'%20y2='-0.49988'%20gradientUnits='userSpaceOnUse'%3e%3cstop%20stop-color='%23666666'/%3e%3cstop%20offset='0.336538'%20stop-color='white'/%3e%3cstop%20offset='0.495192'%20stop-color='white'/%3e%3cstop%20offset='0.653846'%20stop-color='white'/%3e%3cstop%20offset='1'%20stop-color='%23666666'/%3e%3c/linearGradient%3e%3clinearGradient%20id='paint1_linear_5108_6545'%20x1='15.0391'%20y1='14.5392'%20x2='15.0391'%20y2='0.000106877'%20gradientUnits='userSpaceOnUse'%3e%3cstop%20stop-color='%23585858'/%3e%3cstop%20offset='0.745192'%20stop-color='white'/%3e%3cstop%20offset='1'%20stop-color='white'/%3e%3c/linearGradient%3e%3clinearGradient%20id='paint2_linear_5108_6545'%20x1='0'%20y1='0.5'%20x2='29.0783'%20y2='0.5'%20gradientUnits='userSpaceOnUse'%3e%3cstop%20stop-color='%23666666'/%3e%3cstop%20offset='0.336538'%20stop-color='white'/%3e%3cstop%20offset='0.495192'%20stop-color='white'/%3e%3cstop%20offset='0.653846'%20stop-color='white'/%3e%3cstop%20offset='1'%20stop-color='%23666666'/%3e%3c/linearGradient%3e%3clinearGradient%20id='paint3_linear_5108_6545'%20x1='0'%20y1='0.5'%20x2='14.5391'%20y2='0.5'%20gradientUnits='userSpaceOnUse'%3e%3cstop%20stop-color='%23585858'/%3e%3cstop%20offset='0.745192'%20stop-color='white'/%3e%3cstop%20offset='1'%20stop-color='white'/%3e%3c/linearGradient%3e%3c/defs%3e%3c/svg%3e)
We believe exceptional intelligence deserves exceptional pay. Our platform consistently offers rates above the industry average, rewarding experts for their true value and real impact on frontier AI. Here, your expertise isn't just appreciated—it's properly compensated.
No office. No commute. No constraints. Our fully remote workflow gives experts complete flexibility to work at their own pace, from any country, any time zone. You focus on meaningful tasks—we handle the rest.
AI trainers are the heart of our company. We treat every expert with trust, humanity, and genuine appreciation. From personalized support to transparent communication, we build long-term relationships rooted in respect and care.
Ready to Shape the Future of Engineering?
Apply Now.