Lead Engineer, AI Quality - Circle

About Us

Circle is building the world’s leading AI-powered, all-in-one platform for digital businesses. We make it possible for creators, coaches, educators, and businesses to bring together their audience with engaging discussions, live streams, events, chat, courses, and payments — all in one place, all under their own brand.

We’re proud to be a fully remote company of around 270 team members from 30+ countries around the world. We collaborate across time zones, are highly async, and value documentation. Twice a year, we bring the whole company together in beautiful places around the world for our company offsites.

About the Role

The AI Quality engineering team at Circle owns the foundation for measuring, diagnosing, and improving the quality of Circle's AI-powered features. This team focuses on building the infrastructure to measure, diagnose, and improve production AI systems, rather than ML research or model training.

We're looking for a Lead Engineer to help us build out the evaluation frameworks, observability tooling, and diagnostic infrastructure that tell us whether our AI Agents are working well, where to improve them, and how to make them faster and more cost-efficient. This is a hands-on player-coach role where you’ll also lead and manage the AI Quality engineering team.

What You'll Be Doing

• Build and own our evaluation infrastructure: Design the CI/CD pipelines, scorers, and datasets that tell us whether Circle's AI agents are actually working, from a single tool call to a full multi-turn conversation.
• Diagnose exactly where quality breaks down: Trace failures across the agent pipeline including plan creation vs. execution, tool selection, and tool trajectory in complex areas.
• Grow the datasets that make evaluation possible: Stand up annotation workflows and build out AI-generated and simulated conversations.
• Run structured experiments: Evaluate new and open-source models against our production baseline and chase cost and latency wins.
• Lead and grow the team: Set technical direction and manage day-to-day priorities while staying hands-on in the code.
• Partner closely with AI Core engineering: Work with product AI engineers to ensure changes genuinely improve quality.

What You'll Need to Be Successful

• 7+ years of experience building and shipping production software, ideally including LLM-powered agents taking real actions in a product.
• Proficiency in Ruby on Rails / Python or readiness to pick them up quickly.
• Experience building evaluation or observability infrastructure for ML/AI systems (e.g., Braintrust, LangSmith).
• Experience designing datasets, annotation workflows, or labeling pipelines for ML/AI evaluation.
• Ability to learn fast, experiment aggressively, and thrive in a dynamic, ambiguous environment.
• Strong alignment with Circle's company values and C2/Level 5 proficiency in English.

Compensation & Benefits

• U.S.-benchmarked compensation globally
• Equity in the company with ongoing refresh grants
• 35 days of paid time off each year
• Regular company retreats in destinations worldwide
• Comprehensive benefits supporting health, wellbeing, and professional growth