28th March 2026
Introduction Python remains a dominant backend language, but the choice of framework significantly impacts performance, scalability, and developer productivity. Two leading frameworks—Flask and FastAPI—represent different eras of backend design: This article presents a quantitative and architectural comparison to help engineers make informed decisions. 1. Architecture: WSGI vs ASGI Flask (WSGI) FastAPI (ASGI) Key Insight Feature Flask (WSGI) FastAPI (ASGI) Concurrency Model Blocking Non-blocking WebSockets No native Native Async Support Limited First-class 2. Performance Benchmarks Raw Throughput (Requests per Second) Framework RPS (Approx) Flask 2,000 – 5,000 FastAPI 15,000 – 30,000 Benchmarks based on Starlette/Uvicorn vs Flask/Gunicorn under similar hardware conditions. […]








