FastAPI
The most popular modern Python web framework for building APIs. FastAPI leverages Python type hints for automatic validation, serialization, and interactive OpenAPI docs. One of the fastest Python frameworks available.
Why FastAPI?
You're building a Python REST API or microservice
You want automatic API docs (Swagger/OpenAPI) with zero configuration
You need async support and high performance for Python
Signal Breakdown
What drives the Trust Score
Download Trend
Last 12 months
Tradeoffs & Caveats
Know before you commitYou need a full-stack framework with templating (Django is better)
You're building a simple script, not a web service
Your team only knows synchronous Python and async is a new concept
Pricing
Free tier & paid plans
100% free, open-source (MIT)
Free & open-source
Hosting cost only — the framework is free
Alternative Tools
Other options worth considering
The most widely used Node.js web framework. Express is minimal and flexible, giving you full control over your server setup. Despite being older, it remains the most downloaded backend framework in the npm ecosystem by a wide margin.
Often Used Together
Complementary tools that pair well with FastAPI
Learning Resources
Docs, videos, tutorials, and courses
Get Started
Repository and installation options
View on GitHub
github.com/fastapi/fastapi
pip install fastapi uvicornQuick Start
Copy and adapt to get going fast
from fastapi import FastAPI
from pydantic import BaseModel
app = FastAPI()
class Tool(BaseModel):
name: str
trust_score: int
category: str
@app.get("/tools")
async def list_tools():
return {"tools": await db.fetch_all("SELECT * FROM tools")}
@app.post("/tools", status_code=201)
async def create_tool(tool: Tool):
id = await db.execute("INSERT INTO tools ...", tool.dict())
return {"id": id, **tool.dict()}
# Run: uvicorn main:app --reload
# Docs: http://localhost:8000/docsCode Examples
Common usage patterns
Dependency injection
Share database connections and auth via FastAPI depends
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
async def get_current_user(token: str = Depends(oauth2_scheme)):
user = await verify_token(token)
if not user:
raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED)
return user
@app.get("/me")
async def read_me(user = Depends(get_current_user)):
return userBackground tasks
Run async tasks after returning a response
from fastapi import BackgroundTasks
def send_welcome_email(email: str):
# Runs after response is sent
email_service.send(email, subject="Welcome!")
@app.post("/users")
async def create_user(user: UserCreate, background_tasks: BackgroundTasks):
new_user = await db.create_user(user)
background_tasks.add_task(send_welcome_email, user.email)
return new_userStreaming response
Stream large responses with StreamingResponse
from fastapi.responses import StreamingResponse
import asyncio
async def event_stream():
for i in range(10):
yield f"data: chunk {i}
"
await asyncio.sleep(0.5)
@app.get("/stream")
async def stream():
return StreamingResponse(event_stream(), media_type="text/event-stream")Community Notes
Real experiences from developers who've used this tool