Captcha Non PHP

Does anyone know of any good solutions to implement CAPTCHA on a form that cannot use php?

I a开发者_C百科m able to use PHP but only in an external file. Javascript anywhere

Use reCAPTCHA. You can validate it using almost any programming language that can access a web service - so every language that contains some way to make network connections.

Are you able to have an external (in the folder, but not affiliated with the form you're trying to use) PHP file, or does it have to be completely PHP-free?

Because I was going to suggest just doing a POST request to that file using JS.