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

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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.

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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.