Source : WordNet®

for free
     adv : without payment; "I'll give you this gratis" [syn: {gratis},
            {free of charge}]

Source : Free On-Line Dictionary of Computing

for free
     
        Said of a capability of a programming language or hardware
        equipment 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.
     
        [{Jargon File}]
     
        (1994-12-14)