Senior Platform Engineer (Founding Role) – Reinforcement Learning Environments for AI

About the job

This role is being recruited by CoffeeSpace on behalf of an anonymous startup focused on developing realistic environments for training frontier AI agents, particularly in finance workflows.

We’re identifying exceptional technical staff from our network. If there’s a strong fit, we’ll introduce you directly to the founding team.

Location: San Francisco, California, United States

Compensation: $200K–$250K base + 0.15–0.3% equity

Employment type: Full-time

Visa: Visa sponsorship available, including H-1B transfers, TN, and STEM OPT

About the company

This company specializes in creating realistic reinforcement learning environments for frontier AI models, with a focus on financial services. They have a small team of around 10 people and have recently raised $6M at an $80M valuation. Their customers include major AI companies like OpenAI and Anthropic.

The company’s mission is to build software that significantly enhances the quality and throughput of RL environment creation. They are working on innovative synthetic data pipelines and platform analytics to support scalable customer usage.

About the role

As a founding member of the technical staff, you will own platform engineering and play a crucial role in building the engineering organization from the ground up. You will develop infrastructure for RL environment training and inference, innovate on synthetic data pipelines, and establish engineering culture and practices.

What You’ll Do

• Build RL environment training/inference infrastructure to support customer usage at scale
• Research and develop next-generation RL environments that are realistic and long-horizon
• Innovate on synthetic data pipelines to create realistic problems
• Create platform analytics to track data on RL environment costs and bottlenecks
• Craft domain-specific verifiers for financial services verticals
• Establish engineering culture and practices from the ground up

Why This Role Is Compelling

• Work with leading AI companies like OpenAI and Anthropic
• Contribute to a startup with strong growth and financial backing
• Develop RL platforms for high-impact finance workflows
• Enjoy strong benefits including fully covered healthcare, relocation stipend, and 401k match

The Ideal Candidate

• 5–12 years of experience in a technical role
• Familiarity with building evaluations, benchmarks, and RL for AI agents
• Ability to iterate quickly and prioritize a large roadmap of features
• Comfortable with client-facing interactions
• Experience with Python, TypeScript, Docker, AWS, and AI tools

Nice To Have

• Research background in training models or publishing papers
• Experience as a founder or in early-stage startups

Next steps

• 1. Apply via this LinkedIn job post
• 2. We’ll review and reach out if there’s a strong match
• 3. If aligned, we’ll introduce you directly to the team
• 4. If this role isn’t the right fit, we may suggest and make introductions to other high-signal startup roles we’re recruiting for, always with your permission.

A quick note on authenticity

This is a real, active role that CoffeeSpace is recruiting for in close partnership with the hiring team. We don’t post speculative roles and work directly with teams on their actual hiring needs.