In example of login procedure via Zabbix API contents fragment of code:

{
"jsonrpc":"2.0",
"method":"user.login",
"params":

{ "user":"Admin", "password":"zabbix" }

,
"id":1
}

It 's wrong, method "user.login" not supported in API. After send this request to API script i recieved response:

{"jsonrpc":"2.0","error":

{"code":-32602,"message":"Invalid params.","data":"Not authorized"}

,"id":6326}

Correct method of authentification is "user.authenticate".