Lead Engineer, AI Platform

Circle builds an all-in-one platform for creators and businesses to run their communities, courses, events and payments. It is a fully remote company of around 270 people across more than 30 countries, working async and coming together twice a year for retreats.

This lead engineer runs the AI Quality team, which builds the infrastructure that tells Circle whether its AI agents are actually working. That means eval pipelines in CI/CD, scorers and datasets, tracing failures across planning, tool selection and multi-step workflows, building annotation and simulated-conversation pipelines, and running experiments across prompts, models and the agent harness to improve quality, cost and latency. It is a player-coach role: you set technical direction and manage the team while staying hands-on in the code.

Circle wants 7+ years of shipping production software, ideally including tool-using LLM agents, plus experience building evaluation or observability infrastructure for AI systems with tools such as Braintrust or LangSmith. The production stack is Ruby on Rails, with Python for data and evaluation work. Fluent English at a very high level is required.

Pay is $170,000 a year in cash, benchmarked to the US and offered globally, plus equity and 35 days of paid time off. Remote from anywhere.