sending url to different server

[Barrikor]

If by "end user" you mean a random person browsing the webpage that's using the script you wrote, then yes you can do it without them knowing.

Anyone who wants to add your script to their site will read through the code and see it though. It could give them some doubts about your code if you don't explain it. (On the other extreme it could bog down your server if your script ever got popular) IMHO, I see it as a lose/lose...

[Barrikor]

Anyone who knows how to add the script to their site/project will read through the code and see it... even if you hide it with something inconspicuous like <img src="your-site/image.php"> someone will find it and make it public, possibly eroding the trust people have in your product.

IMHO I don't think that approach is very workable, I could be wrong though.