Python / FastAPI Example

pip install fastapi uvicorn stripe python-dotenv

from fastapi import FastAPI, Request, HTTPException
from pydantic import BaseModel
import stripe
import hmac
import hashlib
import base64
import uuid
from datetime import datetime, timedelta
 
app = FastAPI()
stripe.api_key = "sk_test_..."
SIGNING_SECRET = "your_secret"
 
sessions = {}
 
class CartItem(BaseModel):
    product_id: str
    quantity: int
 
class CreateSessionRequest(BaseModel):
    cart_items: list[CartItem]
    currency: str = "USD"
 
class PaymentData(BaseModel):
    token: str
    provider: str = "stripe"
 
class CompleteRequest(BaseModel):
    payment_data: PaymentData
 
def verify_signature(request: Request):
    signature = request.headers.get("signature")
    timestamp = request.headers.get("timestamp")
    body = request.body()
 
    expected = base64.b64encode(
        hmac.new(
            SIGNING_SECRET.encode(),
            f"{timestamp}.{body.decode()}".encode(),
            hashlib.sha256
        ).digest()
    ).decode()
 
    if not hmac.compare_digest(signature, expected):
        raise HTTPException(401, {"error": {"code": "invalid_signature"}})
 
@app.post("/checkout_sessions")
async def create_session(body: CreateSessionRequest):
    session_id = f"cs_{uuid.uuid4().hex[:24]}"
    session = {
        "checkout_session_id": session_id,
        "state": "ready_for_payment",
        "cart": {"items": [item.dict() for item in body.cart_items]},
        "totals": {"total": 2999},
        "expires_at": (datetime.utcnow() + timedelta(minutes=30)).isoformat(),
    }
    sessions[session_id] = session
    return session
 
@app.post("/checkout_sessions/{session_id}/complete")
async def complete_checkout(session_id: str, body: CompleteRequest):
    session = sessions.get(session_id)
    if not session:
        raise HTTPException(404, {"error": {"code": "session_not_found"}})
 
    try:
        stripe.PaymentIntent.create(
            amount=session["totals"]["total"],
            currency="usd",
            payment_method=body.payment_data.token,
            confirm=True,
            payment_method_options={"card": {"request_delegated_payment": True}},
        )
 
        session["state"] = "completed"
        session["order"] = {
            "order_id": f"ord_{uuid.uuid4().hex[:16]}",
            "status": "confirmed",
        }
        return session
    except stripe.error.CardError:
        raise HTTPException(400, {"error": {"code": "payment_declined"}})
 
if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8000)

uvicorn main:app --reload --port 8000