Python Implementation

Password Request

import requests
request = requests.get('https://leakedpassword.com/api/?p={your-password}')
print request.json()

SHA1 Hash Request

import requests
request = requests.get('https://leakedpassword.com/api/?s={your-sha1-hash}')
print request.json()

Response

{
    "password": {
        "leak": true,
        "hash": "7110eda4d09e062aa5e4a390b0a572ac0d2c0220",
        "seen": 1256907
    }
}