for free definition, from Internet Connection, Inc.

[common] Said of a capability of a programming language or hardware that is available by its design without needing cleverness to implement: “In APL, we get the matrix operations for free.” “And owing to the way revisions are stored in this system, you get revision trees for free.” The term usually refers to a serendipitous feature of doing things a certain way (compare big win), but it may refer to an intentional but secondary feature.