I Built a Password Strength Analyzer API with Python + FastAPI 🔐

As a backend developer, I wanted to build something useful, real, and monetizable — not just another tutorial project.

So I built a Password Strength Analyzer API that any developer can integrate into their app in minutes.

What it does

• Returns a strength score from 0 (very weak) to 4 (very strong)
• Estimates crack time using real-world attack scenarios
• Detects if the password is in known breach lists
• Returns actionable suggestions to improve security
• Analyzes uppercase, lowercase, numbers and symbols

Tech Stack

• Python 3.10+
• FastAPI — for the REST API
• zxcvbn — the same algorithm Dropbox uses
• Pydantic — data validation
• Render — cloud deployment

Example Request

curl -X POST "https://password-analyzern.onrender.com/analyze" \
     -H "Content-Type: application/json" \
     -H "X-API-Key: YOUR_API_KEY" \
     -d '{"password": "MyP@ssw0rd!"}'

Example Response

{
  "password": "***********",
  "score": 3,
  "strength_label": "Fuerte 🟢",
  "crack_time": "3 months",
  "suggestions": ["Idealmente usa 12 o más caracteres"],
  "warnings": [],
  "length": 11,
  "has_uppercase": true,
  "has_lowercase": true,
  "has_numbers": true,
  "has_symbols": true,
  "is_common": false
}

Try it for free

RapidAPI (free plan available):
https://rapidapi.com/PabsCueto/api/password-strength-analyzer1

GitHub:
https://github.com/PabsCueto/password-analyzer

Live docs:
https://password-analyzern.onrender.com/docs

---

Built this as part of my API portfolio. Feedback welcome!