POST /json-api/v4/ HTTP/1.1
Host: api.direct.yandex.ru
Content-Length: 76
Content-Type: application/json; charset=utf-8

{
    "method": "GetClientInfo",
    "param": ["agrom"],
    "locale": "ru"
}

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, IdIOHandler,
  IdIOHandlerSocket, IdIOHandlerStack, IdSSL, IdSSLOpenSSL, IdBaseComponent,
  IdComponent, IdTCPConnection, IdTCPClient, IdHTTP;

type
  TForm1 = class(TForm)
    IdHTTP1: TIdHTTP;
    IdSSLIOHandlerSocketOpenSSL1: TIdSSLIOHandlerSocketOpenSSL;
    Memo1: TMemo;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
PostData:TStringList;
html:WideString;
begin
try
PostData:=TStringList.Create;
PostData.Clear;
PostData.Add(Utf8Encode('"method" : "GetClientInfo"'));
PostData.Add(Utf8Encode('"param":"spit-malish",'));
PostData.Add(Utf8Encode('"locale":"ru"'));
PostData.Add(Utf8Encode('"login":"spit-malish",'));
PostData.Add(Utf8Encode('"application_id":"тут_код_моего_приложения"'));
PostData.Add(Utf8Encode('"token":"тут_токен_моего_приложения"'));
IdSSLIOHandlerSocketOpenSSL1 := TIdSSLIOHandlerSocketOpenSSL.Create(nil);
IdSSLIOHandlerSocketOpenSSL1.Destination := IdHTTP1.Request.Host;
IdSSLIOHandlerSocketOpenSSL1.Host := IdHTTP1.Request.Host;
IdSSLIOHandlerSocketOpenSSL1.Port := 443;
IdSSLIOHandlerSocketOpenSSL1.DefaultPort := 0;
IdSSLIOHandlerSocketOpenSSL1.SSLOptions.Method := sslvSSLv2;
IdSSLIOHandlerSocketOpenSSL1.SSLOptions.Mode := sslmUnassigned;
IdHTTP1.Connect;
if IdSSLIOHandlerSocketOpenSSL1.Connected then Showmessage('connected');

IdHTTP1.Request.ContentLength:=PostData.Count;
IdHTTP1.Post('https://api.direct.yandex.ru/v4/json',PostData);
PostData.Free;
except
on e:Exception do
PostData.Free;
end;
Memo1.Text:=IdHTTP1.Response.ResponseText;
end;

end.