repoze.who is an identification and authentication framework for arbitrary WSGI applications. repoze.who can be configured either as WSGI middleware or as an API for use by an application.
repoze.who is inspired by Zope 2's Pluggable Authentication Service (PAS) (but repoze.who is not dependent on Zope in any way; it is useful for any WSGI application). It provides no facility for authorization (ensuring whether a user can or cannot perform the operation implied by the request). This is considered to be the domain of the WSGI application.