Get OAuth2 Access Token from Twitter

GetTwitterOAuth2Token.pas

const
  cAuth = 'YourKeyAndSecret';
  
procedure TForm1.Button1Click(Sender: TObject);
var
  LHTTP: THTTPClient;
  LResponse: IHTTPResponse;
  LContent: TStream;
  LBase64: TBase64Encoding;
begin
  LHTTP := THTTPClient.Create;
  try
    LHTTP.ContentType := 'application/x-www-form-urlencoded';
    LBase64 := TBase64Encoding.Create(0, '');
    try
      LHTTP.CustomHeaders['Authorization'] := 'Basic ' + LBase64.Encode(cAuth);
    finally
      LBase64.Free;
    end;
    LContent := TStringStream.Create('grant_type=client_credentials');
    try
      LResponse := LHTTP.Post('https://api.twitter.com/oauth2/token', LContent);
    finally
      LContent.Free;
    end;
  finally
    LHTTP.Free;
  end;
end;