Creating own tokens

I am trying to understand the process of generating my own, Ethereum based tokens.

My understand is that you need to write a smart contract in the Solidity programming language to create your own ERC20 tokens.

But I came across a site named https://tokenmint.io/ that promises to create tokens without coding ("Create Your Own Ethereum Smart Contracts Without Coding").

Now how legit is a site like that? Don't they have access to all the secrets / keys when they generate the tokens?

Any comments? Recommended reading about how to create your own ERC20 token?