Are there any free testing servers I could use to test and see if the issue actually is with my server

I've been trying to get some PHP script to work, but to no success so far. I've looked up online and found out that it could be a problem with my server's configuration.

Are there any free testing servers I could use to test and see if the problem actually is with my server? The PHP file I'm trying to get to work is one that I'm pointing to in the Paypal IPN handler URL - so I need a server I can upload a file to, not just paste and execute code.

Thank you all in advance.

PS: I need one that is online/ Remote, not something localhost like XAMPP, WAMP