Retreive default browser path

uses

  Registry;

procedure TForm1.Button1Click(Sender: TObject);

var

  Reg: TRegistry;

  KeyName: string;

  ValueStr: string;

begin

  Reg := TRegistry.Create;

  try

    Reg.RootKey := HKEY_CLASSES_ROOT;

    KeyName     := 'htmlfile\shell\open\command';

    if Reg.OpenKey(KeyName, False) then

    begin

      ValueStr := Reg.ReadString('');

      Reg.CloseKey;

      ShowMessage(ValueStr);

    end

    else

      ShowMessage('There isn't a default browser');

  finally

    Reg.Free;

  end;

end;

var

    Path: array[0..255] of char;

begin

  CloseHandle(CreateFile('C:\default.html', GENERIC_WRITE, FILE_SHARE_WRITE, nil, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0));

  FindExecutable('C:\default.html', nil, Path); //Find the executable (default browser) associated with the html file.

  DeleteFile('C:\default.html');

  Showmessage(Path);

end;