2 ms·

Emacs Lisp would probably rank even higher.

• AnIdiotOnTheNet 5y ago
  Or DOS. You can run DOSBox on anything including a web browser.
  • tazjin 5y ago
    Parent said GUI though.
    • AnIdiotOnTheNet 5y ago
      You can run GUIs on DOS. A lot of DOS software had GUIs.