At Polarsteps recently migrated its core API from Flask to FastAPI. In this talk, I’ll walk through the technical and organizational reasons that led to this decision, the challenges we faced during the migration, and the improvements we saw after switching.

We’ll look at how FastAPI’s type hints, automatic docs, and async support helped improve developer experience, onboarding, and performance. I’ll share how we managed the transition from Flask, including strategies to handle legacy code and shared dependencies.

This is a practical talk for engineers and teams considering FastAPI in production. Going over what worked, what didn’t, and what we’d do differently if we had to do it again.