A basic thing to consider about WTFPL is that it's essentially equivalent to public domain, which doesn't exist in some countries, making your software unusable

A basic thing to consider about WTFPL is that it's essentially equivalent to public domain, which doesn't exist in some countries, making your software unusable in those countries. Developers seem to love this license because it's cute, short, and uses foul language, but it's a license that no one should use.