  The integration of differential equations of Feynman integrals can be greatly
facilitated by using a canonical basis. This paper presents the Mathematica
package CANONICA, which implements a recently developed algorithm to automatize
the transformation to a canonical basis. This represents the first publicly
available implementation suitable for differential equations depending on
multiple scales. In addition to the presentation of the package, this paper
extends the description of some aspects of the algorithm, including a proof of
the uniqueness of canonical forms up to constant transformations.
