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 like to document a lot. 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 against an ambitious and growing roadmap.

What you'll be doing

• Build and own our evaluation infrastructure: Design CI/CD pipelines, scorers, and datasets to evaluate Circle's AI agents (planners, tool-callers, and sub-agents) from a single tool call to a full multi-turn conversation.
• Diagnose quality bottlenecks: Trace failures across the agent pipeline including plan creation vs. execution, tool selection, and tool trajectory in complex areas like workflows, site builder, and analytics.
• Grow evaluation datasets: Stand up annotation workflows and build out AI-generated and simulated conversations to cover more of the product faster.
• Run structured experiments: Evaluate new and open-source models against our production baseline, build frameworks for model shifting, and pursue cost/latency optimization.
• Lead and grow the team: Set technical direction, manage day-to-day priorities, and remain hands-on in the codebase.
• Partner with AI Core engineering: Work with product engineering teams to ensure changes measurably improve quality.

What you'll need to be successful

• 7+ years of experience building and shipping production software, ideally including LLM-powered agents that take real actions in a product.
• Proficiency in Ruby on Rails / Python or readiness to pick them up quickly (Ruby on Rails is the foundation for Circle’s AI Agents; Python is a strong plus for data/eval work).
• 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.
• Strong bias for experimentation, fast learning, and thriving in dynamic, ambiguous environments.
• Proficiency in English (CEFR Level C2 / ILR Level 5).

Compensation & benefits

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