This content originally appeared on DEV Community and was authored by William Andrews
I recently built and deployed my first API — an email validation
tool built with Python and FastAPI. Here's how I did it and what
I learned along the way.
Why Email Validation?
Every app that accepts user signups needs email validation.
Most developers either roll their own regex (which misses a lot)
or pay too much for an enterprise solution. I wanted to build
something simple, affordable, and reliable.
What It Does
The API checks email addresses for:
- Format — RFC 5322 compliance
- MX Records — confirms the domain actually receives email
- Disposable domains — flags throwaway addresses like mailinator.com
- Typos — catches mistakes like gmial.com and suggests gmail.com
Each response includes a 0-100 quality score.
The Tech Stack
- Python — FastAPI for the web framework
- dnspython — for MX record lookups
- Railway — for deployment
- RapidAPI — for distribution and billing
Quick Example
import requests
url = "https://email-validation52.p.rapidapi.com/validate"
params = {"email": "test@gmail.com"}
headers = {
"X-RapidAPI-Key": "YOUR_API_KEY",
"X-RapidAPI-Host": "email-validation52.p.rapidapi.com"
}
response = requests.get(url, headers=headers, params=params)
print(response.json())
Example Response
{
"email": "test@gmail.com",
"is_valid": true,
"score": 95,
"checks": {
"format": true,
"mx_record": true,
"disposable": false,
"typo": false
},
"suggestion": null,
"elapsed_ms": 245
}
What I Learned
FastAPI is incredible for building APIs quickly. It generates
interactive documentation automatically at /docs which makes
testing and sharing your API effortless.
Deploying to Railway was surprisingly simple — connect your
GitHub repo and it handles everything else.
The hardest part wasn't the code. It was getting all the pieces
working together — deployment, billing, documentation. But once
it clicked it all made sense.
Try It Free
I listed it on RapidAPI with a free tier of 500 requests/month.
https://rapidapi.com/Willivan0706/api/email-validation52
Would love feedback from anyone who works with email validation
or has built APIs before!
This content originally appeared on DEV Community and was authored by William Andrews
William Andrews | Sciencx (2026-03-21T20:10:18+00:00) How I Built and Deployed a Free Email Validation API with Python and FastAPI. Retrieved from https://www.scien.cx/2026/03/21/how-i-built-and-deployed-a-free-email-validation-api-with-python-and-fastapi/
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