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Flask vs FastAPI
Trust Score comparison · March 2026
Signal Comparison
12M / wkPyPI downloads18.4M / mo
60 commitsCommits (90d)98 commits
68k ★GitHub stars78k ★
120k q'sStack Overflow14k q's
HighCommunityVery High
FlaskFastAPI
Key Differences
| Factor | Flask | FastAPI |
|---|---|---|
| License | BSD 3-Clause | MIT |
| Language | Python | Python |
| Hosted | Self-hosted | Self-hosted |
| Free tier | — | ✓ Yes |
| Open Source | ✓ Yes | ✓ Yes |
| TypeScript | — | — |
Pick Flask if…
- Small to medium Python APIs where you want full control over the stack
- Prototyping quickly without a framework imposing structure
- ML model serving where a lightweight HTTP wrapper is all you need
Pick FastAPI if…
- 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
Side-by-side Quick Start
Flask
from flask import Flask, jsonify
app = Flask(__name__)
@app.route('/api/hello')
def hello():
return jsonify(message='Hello from Flask!')
if __name__ == '__main__':
app.run(debug=True)FastAPI
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/docsCommunity Verdict
Based on upvoted notes🏆
FastAPI wins this comparison
Trust Score 97 vs 86 · 11-point difference
FastAPI leads on Trust Score with stronger signal data across downloads and community health. That said, the other tool is worth considering if your use case matches its specific strengths above.