Research Scientist/ Research Engineer

Collinear AI, Inc.; Sunnyvale (CA); On-site; USD 160,000 - 350,000; Full time

Benefits offered by this job

Comprehensive medical, dental, and vision coverage

10 company holidays and flexible PTO

12 weeks of paid parental leave

ClassPass membership

Regular in-office lunches

Job summary

Collinear AI, Inc. is seeking a Research Scientist or Engineer in Sunnyvale, California, to help build cutting-edge AI systems. You will design high-fidelity environments and evaluations that advanced AI labs rely on, bridging the gap between research and practical applications. Ideal candidates possess a strong technical foundation, experience in reinforcement learning, and a knack for creating robust infrastructures. The role offers competitive salary packages with equity and significant impact potential within a dynamic startup environment.

Qualifications

• A strong foundation in software engineering to build robust infrastructure.
• Experience with reinforcement learning and simulation systems.
• Ability to design high-fidelity environments for AI.

Responsibilities

• Design and implement ultra-realistic simulation environments.
• Develop policy-aware evaluations to measure capability and safety.
• Iterate on the ML stack and ensure developer-friendly tools.
• Collaborate with founders to push the state-of-the-art in AI reliability.

Skills

Technical depth

Research intuition

High agency

Software engineering

Reinforcement Learning

Education

Bachelor's, Master's, or PhD in CS, Math, Physics, etc.

Tools

Python

Job description

Collinear is a research-focused AI company building systems that make intelligent models more reliable, aligned, and useful in real-world settings. We work across post-training, RL, distillation, and evaluation to help teams get practical reasoning and behavior from open-source models. Our approach is grounded in technical rigor, clear thinking, and building tools that last.

How We Work

We operate with very little bureaucracy, which means decisions are made quickly and ideas move straight into action. Everyone has real ownership and is trusted to learn fast, ask questions, and figure out how to unblock themselves when the path is not obvious. We expect clear communication, thoughtful judgment, and a focus on impact rather than process. You will work closely with teammates who care deeply about the craft and the mission.

Who Thrives Here

People who enjoy solving hard problems, take initiative, and do not need hand holding tend to thrive at Collinear. If you like autonomy, fast decision cycles, and collaborating with others who hold a high bar for clarity and execution, you will feel at home here. This is a place for builders who want their work to matter and to be felt immediately.

Comprehensive medical, dental, and vision coverage

10 company holidays and flexible PTO to rest, recharge, and take care of personal needs

12 weeks of paid parental leave for all new parents

ClassPass membership for fitness, wellness, and recovery

Regular in-office lunches to make your day smoother

Learning & Growth

Team-driven events, lunches, and opportunities to connect

Conference support for employees with published papers

Close collaboration with founders, research scientists, and engineering leads

High-impact ownership across projects, features, and research areas

Exposure to advanced LLM evaluation, post-training workflows, and emerging techniques for improving model performance

Startup environment where your work directly shapes the company

Competitive base salary tailored to your experience and scope of impact

Meaningful equity ownership for full-time team members

Relocation bonuses for candidates moving to join the team

Work with us

At Collinear, we're revolutionizing how enterprises deploy and scale AI safely and reliably. If this resonates with you, we’d love to connect.

Research Scientist/ Research Engineer

Location

Sunnyvale, California

Employment Type

Full time

Department

Research

Compensation

About Collinear

At Collinear, we help teams fearlessly ship AI.

Frontier labs and AI-native companies use our SimLab to find capability gaps in their agents and generate high-quality data to close them. We believe that the next generation of AI progress won't come from just bigger models, but from more rigorous, long-horizon simulation and programmatic verification.

SimLab allows researchers to spin up realistic environments, run agents through complex tasks, and surface failure modes under real-world conditions. We then close the loop by generating targeted synthetic data to retrain models, delivering measurable quality lift on the metrics that actually matter.

About the Role

We are looking for Research Scientists and Research Engineers to help us build the data engine for frontier AI. In this role, you will bridge the gap between frontier research and production engineering. You will develop the high-fidelity environments and evaluation stacks that the world’s leading AI labs rely on to stress-test their most advanced agents. Your work will involve iterating on novel RL approaches and translating them into robust, scalable infrastructure that moves the needle on real-world model metrics.

Responsibilities

Build Agentic Environments: Design and implement the next generation of "SimLabs", ultra-realistic, long-horizon simulation environments where agents learn to navigate ambiguity and maintain context.

Programmatic Verification: Develop rigorous, policy-aware judges and evaluations that measure genuine capability and safety beyond simple benchmarks.

Close the Loop: Design and execute high-quality post-training runs (CPT, SFT, RL) to deliver frontier performance on open-source models using curated, high-signal data.

Rapid Iteration: Debug and iterate across the full ML stack, from infrastructure to model behavior, ensuring our tools remain "command-line first" and developer-friendly.

Collaborate: Work daily with the founders and research staff to shape the roadmap and push the state-of-the-art in AI reliability.

About You

We are looking for individuals who demonstrate a rare combination of technical depth, research intuition, and high agency.

Technical Foundation: A Bachelor’s, Master’s, or PhD in a technical field (CS, Math, Physics, etc.), or a demonstrated "proof of work" through significant open-source contributions or industry experience.

Engineering Rigor: A strong foundation in software engineering with the ability to build robust, scalable infrastructure. You should be comfortable in a Python-friendly, CLI-first development environment.

ML Fluency: A principled understanding of foundation models, including how they are constructed, evaluated, and optimized.

Empirical Mindset: Experience conducting research or technical experiments with a focus on reproducibility and data-driven results.

What will make you stand out

Research Taste: You have a strong intuition for identifying what matters in complex problem spaces. You can balance deep research exploration with the pragmatism needed to ship a product.

Impact-Driven Agency: You care about outcomes, not just activity. You don't wait for a ticket; you identify gaps in the system, build the solution, and ensure it moves real-world metrics for frontier AI labs.

Domain Expertise: Prior experience with Reinforcement Learning (RLHF/RLAIF), simulation systems, or building long-horizon agentic environments.

Proven Track Record: A history of contributing to influential ML research (e.g., publications at NeurIPS, ICLR, ICML) or maintaining high-impact open-source projects.

Post-Training Experience: Experience fine-tuning or evaluating large-scale models to deliver "frontier performance" on open-source benchmarks.

Why Join Collinear

Own the Frontier: Work on the most pressing problem in AI today: making agents reliable enough for production.

High Density of Talent: Join a small, elite team where you will be pushed to do your life's work.

Elite Compensation: We offer competitive salary and equity packages to ensure we attract the best of the best.

Direct Impact: At a seed-backed startup, your work directly shapes the company's trajectory and the future of AI safety.

Collinear is an equal opportunity employer and values diversity. We do not discriminate on the basis of race, color, religion, sex, gender identity, sexual orientation, national origin, age, disability, veteran status, or any other characteristic protected by applicable law.

The base salary range for this role in California is $160,000 to $350,000 per year, depending on experience and qualifications. This role will also be eligible for equity, benefits, and bonuses.

Collinear provides reasonable accommodations for candidates with disabilities throughout the application and hiring process. If you need an accommodation, please contact us.

Pursuant to applicable local ordinances, we will consider qualified applicants with arrest and conviction records.