Calling a RESTful web service using Indy is pretty straight forward.
Add IdHTTP to your uses clause. Remember that IdHTTP needs the “HTTP://” prefix on your URLs.
function GetURLAsString(const aURL: string): string;
var
lHTTP: TIdHTTP;
begin
lHTTP := TIdHTTP.Create;
try
Result := lHTTP.Get(aURL);
finally
lHTTP.Free;
end;
end;