Have you a compound in your lab, which was not successful against the designed target, or
a drug that is no more attractive? The drug repurposing represents the right way to reconsider them. It
can be defined as the modern and rationale approach of the traditional methods adopted in drug discovery,
based on the knowledge, insight and luck, alias known as serendipity. This repurposing approach
can be applied both in silico and in wet. In this review we report the molecular modeling facilities
that can be of huge support in the repurposing of drugs and/or unsuccessful lead compounds. In
the last decades, different methods were proposed to help the scientists in drug design and in drug repurposing.
The steps strongly depend on the approach applied. It could be a ligand or a structure based method, correlated
to the use of specific means. These processes, starting from a compound with potential therapeutic properties and a sizeable
number of toxicity passed tests, can successfully speed up the very slow development of a molecule from bench to
market. Herein, we discuss the facilities available to date, classifying them by methods and types. We have reported a series
of databases, ligand and structure stand-alone software, and of web-based tools, which are free accessible to scientific
community. This review does not claim to be exhaustive, but can be of interest to help in drug repurposing through in
silico methods, as a valuable tool for the medicinal chemistry community.