Function GetHTTPResponsePDF(ByVal sURL As String, Token As String, Metod As String)
    Dim logpass As String
    On Error Resume Next
    Set client = CreateObject("MSXML2.XMLHTTP")
    With client
      .Open "GET", sURL & Metod, False
      .SetRequestHeader "Content-Type", "application/json"
      .SetRequestHeader "AG-TOKEN", Token
      .send
    End With
    
    If client.statustext = "OK" Then
        Set ADOStream = CreateObject("ADODB.Stream")
        ADOStream.Type = 1: ADOStream.Open
        ADOStream.Write client.responseBody
  
        ADOStream.SaveToFile "C:\Рабочие документы\Вспомогательные программы\Отчеты сервиса\" & UserForm1.ListBoxObject.List(UserForm1.ListBoxObject.ListIndex, 0) & "-" & _
                                            UserForm1.ListBoxObject.List(UserForm1.ListBoxObject.ListIndex, 1) & ".pdf", 2
        ADOStream.Close: Set ADOStream = Nothing
        DownloadFile = True
    Else
        'MsgBox "Не удается скачать файл" & XMLHTTP.statustext
    End If
    GetHTTPResponsePDF = client.ResponseText
    Set client = Nothing
End Function

Function GetHTTPResponse(ByVal sURL As String, Token As String, Metod As String)
    Dim logpass As String
    On Error Resume Next
    Set client = CreateObject("MSXML2.XMLHTTP")
    With client
      .Open "GET", sURL & Metod, False
      .SetRequestHeader "Content-Type", "application/json"
      .SetRequestHeader "AG-TOKEN", Token
      .send
       GetHTTPResponse = .ResponseText
    End With
    Set client = Nothing
End Function

Sub WebClient()
 Dim URL As String
URL = "http://95.213.159.8:8300/Login"
json = GetHTTPResponse(URL)
UserForm1.Label1.Caption = json
UserForm1.Show
End Sub
 
Function GetHTTPResponse(ByVal sURL As String)
    Dim logpass As String
    logpass = "{""UserName"":""demo"",""Password"":""demo""}"
    On Error Resume Next
    Set client = CreateObject("MSXML2.XMLHTTP")
    With client
      .Open "POST", sURL, False
      .SetRequestHeader "Content-Type", "application/json"
      .send [logpass]
       GetHTTPResponse = .ResponseText
    End With
     Set client = Nothing
End Function

        .send "{""UserName"":""demo"",""Password"":""demo""}"

WebClient client = new WebClient();
client.Headers["Content-Type"] = "application/json";
client.Headers["AG-TOKEN"] = client.UploadString("http://localhost:8300/Login", "{\"UserName\":\"demo\",\"Password\":\"demo\"}").Trim('\"', '\"');

// далее обычная работа с JSON

client.DownloadString("http://localhost:8300/EnumSchemas");