Does FastAPI Work With Resend?
Yes, FastAPI and Resend work together seamlessly for building email-enabled APIs with minimal friction.
Quick Facts
How FastAPI Works With Resend
FastAPI and Resend integrate cleanly because Resend provides a simple HTTP client library that works with any Python async framework, including FastAPI. You install the Resend Python SDK, authenticate with an API key, and call email methods from your route handlers. FastAPI's async support means you can use `await resend.emails.send()` directly in your endpoints without blocking.
The typical pattern is to install the `resend` package, initialize it with your API key in environment variables, then call it from within FastAPI route handlers. Since Resend is HTTP-based under the hood, there's no complicated connection pooling or special middleware needed. You can send emails on user signup, password resets, notifications, or any other event. For React Email templates, Resend provides a companion library that generates HTML—you can pre-compile templates or generate them dynamically in Python using string formatting or Jinja2.
The developer experience is excellent: Resend handles deliverability, bounce tracking, and opens/clicks through their dashboard, while FastAPI handles the API logic. Error handling is straightforward since Resend raises exceptions on validation or rate-limit issues, which FastAPI can catch and return as proper HTTP responses.
Best Use Cases
Quick Setup
pip install fastapi resend python-dotenv uvicornfrom fastapi import FastAPI
from resend import Resend
import os
from dotenv import load_dotenv
load_dotenv()
app = FastAPI()
client = Resend(api_key=os.getenv("RESEND_API_KEY"))
@app.post("/send-welcome")
async def send_welcome(email: str):
try:
response = client.emails.send({
"from": "onboarding@resend.dev",
"to": email,
"subject": "Welcome!",
"html": "<h1>Thanks for signing up</h1>"
})
return {"status": "sent", "id": response.get("id")}
except Exception as e:
return {"error": str(e)}, 400Known Issues & Gotchas
API key exposure in logs or error messages
Fix: Always use environment variables (python-dotenv), never hardcode keys. Use FastAPI's logging setup to exclude sensitive headers.
Resend has rate limits (100 emails/day on free tier, 300/hour on paid)
Fix: Implement queue-based sending with Celery or Redis Queue for high-volume use cases. Monitor usage via Resend dashboard and set up alerts.
React Email templates must be pre-compiled to HTML or generated server-side
Fix: Use `react-email` CLI to export templates as HTML/JSX, then render with a template engine in Python, or use Resend's `jsx` parameter if available in future SDKs.
Testing sends real emails by default
Fix: Use test addresses (test@resend.dev) in development, or mock the Resend client in unit tests with pytest-mock.
Alternatives
- •SendGrid + FastAPI: More enterprise features (templates, segments), heavier setup
- •Mailgun + FastAPI: Excellent webhook support for bounce/complaint tracking, similar ease of use
- •AWS SES + FastAPI: Lower cost at scale, requires boto3, more operational overhead
Resources
Related Compatibility Guides
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