Django and FastAPI are the two most common ways to build a web backend in Python. They are not really rivals: one is a complete toolkit for web applications, the other a sharp tool for building APIs. The useful question is which shape your product is.
Django: everything included
Django, first released in 2005, calls itself "the web framework for perfectionists with deadlines". Out of the box it brings:
- an ORM and database migrations,
- user accounts, permissions and sessions,
- a generated admin interface for managing data,
- forms, templates and protection against common web attacks.
That admin alone often saves weeks: staff can manage customers, orders or bookings before a single custom screen exists. Django supports asynchronous views, though much of its ecosystem is still written for synchronous code.
FastAPI: an API from your type hints
FastAPI is built on Starlette and Pydantic. You describe each endpoint with ordinary Python type hints, and FastAPI uses them to validate every request and to generate interactive OpenAPI documentation automatically. It is asynchronous from the ground up, which suits work that spends its time waiting on other services — databases, payment providers, AI models.
What it does not include is the rest: there is no built-in ORM, admin or account system. You choose libraries for those (SQLAlchemy is the usual one), which is flexibility if you want it and work if you do not.
Side by side
| Django | FastAPI | |
|---|---|---|
| Best at | Complete web applications | APIs and services |
| Admin interface | Built in | Not included |
| Database layer | Built-in ORM and migrations | Your choice, e.g. SQLAlchemy |
| Accounts and permissions | Built in | Your choice of library |
| API documentation | Via add-ons | Generated automatically |
| Async | Supported | Native |
| HTML pages | Templates built in | Possible, not its focus |
Which to choose
Django, when…
- the product is a web application people log into: a portal, a booking system, a CRM;
- staff need to manage data from the start;
- you want one well-trodden way of doing things that the next developer will recognise.
FastAPI, when…
- the main client is a mobile app or a separate JavaScript front end;
- the work is mostly calling other services, such as AI models or payment providers;
- other systems need a clean, documented API to integrate with.
Both, when…
A Django application for the people running the business and a FastAPI service for the app or the AI workload is a common and sensible split. And for a small site or a single-purpose tool, Flask — smaller than either — is often enough. This site is Flask.
Sources
- Django — Django Software Foundation
- FastAPI documentation — FastAPI