I Recommend threading it, here is a quick threading example that works for fmx. simple project with a button and a memo, uses System.Net.Httpclientcomponent
procedure TForm1.Button1Click (Sender: TObject);
begin
TThread.CreateAnonymousThread (procedure ()
var
body: tstringstream;
http: tnethttpclient;
begin
http: = TNetHTTPClient.Create (nil);
body: = TStringStream.Create;
try
http.Get ( 'https://www.google.com',body);
tthread.Synchronize (nil, procedure
begin
memo1.text: = body.DataString;
end);
finally
http.free;
body.free;
end;
end).Start;
end;