  Session types are becoming popular and have been integrated in several
mainstream programming languages. Nevertheless, while many programming
languages consider asynchronous fifo channel communication, the notion of
subtyping used in session type implementations is the one defined by Gay and
Hole for synchronous communication. This might be because there are several
notions of asynchronous session subtyping, these notions are usually
undecidable, and only recently sound (but not complete) algorithmic
characterizations for these subtypings have been proposed. But the fact that
the definition of asynchronous session subtyping and the theory behind related
algorithms are not easily accessible to non-experts may also prevent further
integration. The aim of this paper, and of the tool presented therein, is to
make the growing body of knowledge about asynchronous session subtyping more
accessible, thus promoting its integration in practical applications of session
types.
