Senior Full-Stack Software Engineer, AI Core

📋 Description

• Ship full-stack AI projects end-to-end on a product built in Ruby on Rails backend and React
• Design and run experiments (A/B tests, AI evaluations) to validate AI features and guide iteration.
• Build and integrate components for AI infrastructure and optimize for performance and reliability
• Improve processes, tools, and systems to scale AI features into production-ready solutions.
• Stay up-to-date with cutting-edge AI research, techniques, and tools.
• Collaborate with Circle's leaders and designers through the feature design process.

🎯 Requirements

• 6+ years as a full-stack engineer on high-traffic production apps with scale challenges.
• Strong proficiency in Ruby on Rails, MySQL / PostgreSQL, ReactJS.
• Hands-on experience building AI features in production (RAG systems, AI agents, or LLM-powered
• Strong experimentation mindset: design/run A/B tests, measure results, iterate quickly.
• Autonomy, accountability, and collaboration in a fast-paced, ambiguous environment.
• Alignment with Circle values and CEFR/C2, ILR Level 5 English proficiency.

🎁 Benefits

• Salary: $130,000 - $140,000 USD per year, with U.S.-benchmarked compensation and equity.
• Remote-first company with global flexibility and generous time off.
• Health, wellbeing, and professional growth benefits; biannual in-person company retreats.