JSON::XS is a Perl module for converting arbitrary Perl data structures to JSON and vice versa. Its primary objectives are to be semantically correct and to run quickly; for the latter goal, the implementation is written in C. . From JSON version 2.0 onward, the JSON module will use JSON::XS to accelerate its work, with no overhead due to emulation (by inheriting the constructor and methods). Using JSON instead of JSON::XS gives you a portable JSON API that can be fast when needed, but doesn't require a C compiler by falling back on a Pure Perl implementation.