python 42 lines · 7 steps

Handling Stripe webhooks in FastAPI

A FastAPI endpoint that verifies Stripe's signature, then routes each event type to the right billing action.

Explained by highlit
FastAPI Intermediate webhooks signature-verification event-routing async payments
1import stripe
2from fastapi import APIRouter, Request, Header, HTTPException
3 
4from app.config import settings
5from app.services.billing import (
6 activate_subscription,
7 mark_payment_failed,
8 cancel_subscription,
9)
10 
11router = APIRouter(prefix="/webhooks", tags=["webhooks"])
12 
13 
14@router.post("/stripe", status_code=200)
15async def handle_stripe_webhook(
16 request: Request,
17 stripe_signature: str = Header(..., alias="Stripe-Signature"),
18):
19 payload = await request.body()
20 
21 try:
22 event = stripe.Webhook.construct_event(
23 payload=payload,
24 sig_header=stripe_signature,
25 secret=settings.STRIPE_WEBHOOK_SECRET,
26 )
27 except ValueError:
28 raise HTTPException(status_code=400, detail="Invalid payload")
29 except stripe.error.SignatureVerificationError:
30 raise HTTPException(status_code=400, detail="Invalid signature")
31 
32 obj = event["data"]["object"]
33 
34 match event["type"]:
35 case "checkout.session.completed":
36 await activate_subscription(obj["customer"], obj["subscription"])
37 case "invoice.payment_failed":
38 await mark_payment_failed(obj["customer"], obj["id"])
39 case "customer.subscription.deleted":
40 await cancel_subscription(obj["customer"])
41 
42 return {"received": True}
01 / 01
STEP 01

Walkthrough

Space play ←→ step click any line
Three takeaways
  1. 1Always verify a webhook's signature against a shared secret before trusting its contents.
  2. 2Read the raw request body for signature checks — parsed JSON won't match the signed bytes.
  3. 3Return 200 quickly and delegate the actual work so the provider considers the event delivered.

Related explainers

python 
from operator import itemgetter
 
 
def sort_employees(employees):

Multi-key sorting patterns in Python

sorting tuple-keys itemgetter
Intermediate 5 steps
javascript 
const express = require('express');
const Stripe = require('stripe');
 
const stripe = new Stripe(process.env.STRIPE_SECRET_KEY);

Verifying Stripe webhooks in Express

webhooks signature-verification raw-body
Intermediate 7 steps
python 
from itertools import islice
from typing import Iterable, Iterator, TypeVar
 
T = TypeVar("T")

Batching an iterable for bulk indexing

generators batching lazy-evaluation
Intermediate 7 steps
python 
import time
from dataclasses import dataclass, field
 
from fastapi import Depends, FastAPI, HTTPException, Request, status

Token-bucket rate limiting in FastAPI

rate-limiting token-bucket dependency-injection
Advanced 10 steps
python 
import argparse
import sys
from pathlib import Path
 

Building a subcommand CLI with argparse

cli argparse subcommands
Intermediate 6 steps
python 
from collections.abc import Mapping
from typing import Any, Iterator
 
 

Flattening nested config into dotted keys

recursion generators tree-traversal
Intermediate 7 steps

Share this explainer

Here's the card — post it anywhere.

Handling Stripe webhooks in FastAPI — share card
Made with highlit — turn any snippet into a walkthrough like this in about a minute.
Explain your code