Open-source software

Open source software, or free software, is software that can be distributed freely in a form that lets others modify it and rebuild it from scratch. While it is known as “free software," it's not necessarily free as in zero-cost: FLOSS programmers can ask for donations, or charge for support or for copies. Linux is an example of a free, open source program, as are Firefox and Tor.

Synonyms: 
FLOSS
free, libre and open-source software
free software
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