C# Implementation

Password Request

var client = new RestClient("https://api.leakedpassword.com/pass/{your-password}");
var request = new RestRequest(Method.GET);
request.AddHeader("Content-Type", "application/json");
request.AddHeader("Accept", "application/json");
request.AddParameter("application/json", "{}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

SHA1 Hash Request

var client = new RestClient("https://api.leakedpassword.com/sha1/{your-sha1-hash}");
var request = new RestRequest(Method.GET);
request.AddHeader("Content-Type", "application/json");
request.AddHeader("Accept", "application/json");
request.AddParameter("application/json", "{}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

Response

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