reference request – Non-specific category theory literature

As always, I start the text by saying that English is not my first language, so if you see one, say it, I like these tips.

But, let's get to the question, I looked a lot in your database and found a nive category theory.
My goal is to generalize certain concepts in some areas that I like to study (as examples, differential geometry, algebraic topology, etc.).
I am looking for a book that explains the structure of category theory in general, not just for an application, so that I can use this structure to generalize the concepts I want, whatever their origin.

To summarize quickly, I want a book in category theory that applies to nothing, it's just the theory of categories in its most abstract form.

And sorry if it's a repeated question, but I could not find something that matches what I need.