Summary: Self-indexes can represent a text in asymptotically optimal space under the $k$-th order entropy model, give access to text substrings, and support indexed pattern searches. Their time complexities are not optimal, however: they always depend on the alphabet size. In this paper we achieve, for the first time, full alphabet-independence in the time complexities of self-indexes, while retaining space optimality. We obtain also some relevant byproducts on compressed suffix trees.