In the case that I have free electricity, is mining worth it? As the title indicates, I have three options that are gonna make me free of charge in terms are electricity, which I describe below:


I have free access to electricity. I can have as much as I want power, to turn on even 10 computers simultaneously.
I do have free access to AWS / Azure servers with a good condition of ram and CPU.
I have huge clients on my website, so I can run some JavaScript's that are mining in their computers, or even implement the code inside a game.


In many places, I have read that mining using a PC doesn't worth the electricity. What about my case? Is it worth to do it? Do you recommend that I buy physical device for mining, or I can use a normal computer?

I have to tell that my Internet is 4G network for free electricity and not a lot of bandwidth.
First, mining does not require a lot of bandwidth. Whatever you have is likely enough. 

Second, mining profits (in bitcoin, not some currency after exchange) is determined by difficulty. Difficulty is like a level number. The higher it is, the harder it is for mining computers to hash (the under-the-hood work). 

Calculating mining profits only needs the current difficulty and your hash rate. Google search "Bitcoin mining calculator" to use one of the many good ones available. 

Regardless of electricity costs, mining on:


computer processors or graphics cards is going to yield a very low profit. Probably not worth your time. 
AWS has probably been discussed before, but again will likely be far too low hashing power to be worth it, plus you'd have the service fees. 
other's computers with JavaScript is a relatively new and interesting idea, but again is such a low hash rate that it's only worth it if you have thousands of clients running your script. There's also the dubious nature of the proposal (do you have permission?).


Mining on specialised hardware, called ASICs, is very profitable if you don't consider electricity. But current models consume much, over 1000W all of them, and are very noisy and push out a lot of heat.