{"slug":"flask-vs-fastapi)","title":"Flask vs FastAPI","url":"https://www.aversusb.net/compare/flask-vs-fastapi)","faqCount":5,"faqs":[{"question":"Which framework should I choose for a new project in 2026?","answer":"Use FastAPI for REST APIs, microservices, or projects prioritizing performance and modern features. Use Flask for traditional web applications, content sites, or if your team is already proficient with Flask. FastAPI has become the standard for new API projects, while Flask remains ideal for full-stack web applications and prototypes."},{"question":"How much faster is FastAPI than Flask really?","answer":"FastAPI handles approximately 25,000 requests/second while Flask handles ~8,000 req/s on identical hardware—a 3x improvement. This difference compounds under concurrent load; FastAPI's native async support prevents thread blocking while Flask requires external ASGI servers. In practice, at 100+ concurrent users, Flask degrades significantly without tuning."},{"question":"Can I migrate a Flask app to FastAPI?","answer":"Partial migrations are feasible—you can run FastAPI and Flask side-by-side, gradually replacing Flask routes with FastAPI endpoints. However, full migration requires rewriting views to FastAPI's dependency injection pattern and replacing Flask extensions with FastAPI-compatible libraries. Most teams do this incrementally or rebuild performance-critical APIs in FastAPI while keeping legacy Flask code."},{"question":"Does Flask have async support now?","answer":"Flask 2.0+ added experimental async/await support, but it's not recommended for production. FastAPI's async implementation is far more mature, using Starlette's ASGI foundation. If you need true async capabilities, FastAPI is the better choice; Flask's async is a compromise for existing Flask users."},{"question":"Which has better documentation?","answer":"FastAPI's official documentation is excellent and modern, with interactive examples. Flask's documentation is comprehensive but assumes more developer knowledge. However, FastAPI auto-generates API documentation (Swagger UI, ReDoc) while Flask requires manual setup—a major advantage for API projects."}],"faqPageSchema":{"@context":"https://schema.org","@type":"FAQPage","@id":"https://www.aversusb.net/compare/flask-vs-fastapi)#faq","url":"https://www.aversusb.net/compare/flask-vs-fastapi)","inLanguage":"en-US","name":"Flask vs FastAPI — FAQ","description":"Frequently asked questions about Flask vs FastAPI","dateModified":"2026-07-07T20:48:18.763Z","author":{"@type":"Organization","@id":"https://www.aversusb.net/#organization","name":"A Versus B"},"publisher":{"@type":"Organization","@id":"https://www.aversusb.net/#organization","name":"A Versus B"},"isPartOf":{"@type":"Article","@id":"https://www.aversusb.net/compare/flask-vs-fastapi)#article"},"license":"https://creativecommons.org/licenses/by/4.0/","speakable":{"@type":"SpeakableSpecification","cssSelector":["#faq",".faq-item"]},"mainEntity":[{"@type":"Question","name":"Which framework should I choose for a new project in 2026?","acceptedAnswer":{"@type":"Answer","text":"Use FastAPI for REST APIs, microservices, or projects prioritizing performance and modern features. Use Flask for traditional web applications, content sites, or if your team is already proficient with Flask. FastAPI has become the standard for new API projects, while Flask remains ideal for full-stack web applications and prototypes.","inLanguage":"en-US","url":"https://www.aversusb.net/compare/flask-vs-fastapi)"}},{"@type":"Question","name":"How much faster is FastAPI than Flask really?","acceptedAnswer":{"@type":"Answer","text":"FastAPI handles approximately 25,000 requests/second while Flask handles ~8,000 req/s on identical hardware—a 3x improvement. This difference compounds under concurrent load; FastAPI's native async support prevents thread blocking while Flask requires external ASGI servers. In practice, at 100+ concurrent users, Flask degrades significantly without tuning.","inLanguage":"en-US","url":"https://www.aversusb.net/compare/flask-vs-fastapi)"}},{"@type":"Question","name":"Can I migrate a Flask app to FastAPI?","acceptedAnswer":{"@type":"Answer","text":"Partial migrations are feasible—you can run FastAPI and Flask side-by-side, gradually replacing Flask routes with FastAPI endpoints. However, full migration requires rewriting views to FastAPI's dependency injection pattern and replacing Flask extensions with FastAPI-compatible libraries. Most teams do this incrementally or rebuild performance-critical APIs in FastAPI while keeping legacy Flask code.","inLanguage":"en-US","url":"https://www.aversusb.net/compare/flask-vs-fastapi)"}},{"@type":"Question","name":"Does Flask have async support now?","acceptedAnswer":{"@type":"Answer","text":"Flask 2.0+ added experimental async/await support, but it's not recommended for production. FastAPI's async implementation is far more mature, using Starlette's ASGI foundation. If you need true async capabilities, FastAPI is the better choice; Flask's async is a compromise for existing Flask users.","inLanguage":"en-US","url":"https://www.aversusb.net/compare/flask-vs-fastapi)"}},{"@type":"Question","name":"Which has better documentation?","acceptedAnswer":{"@type":"Answer","text":"FastAPI's official documentation is excellent and modern, with interactive examples. Flask's documentation is comprehensive but assumes more developer knowledge. However, FastAPI auto-generates API documentation (Swagger UI, ReDoc) while Flask requires manual setup—a major advantage for API projects.","inLanguage":"en-US","url":"https://www.aversusb.net/compare/flask-vs-fastapi)"}}]}}