I've been researching on Internet that open-source are free, but I found a bit contradicting fact that there are some packages which are commercial like this.

I too have used some tools like Metasploit which ask for license. Is a product developed by modification of a open-source can be commercial? I'm totally confused!

closed as off-topic by jasonwryan, Anthon, Renan, Stéphane Gimenez, slm Dec 11 '13 at 12:42

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Open source means that the source is open: available to look at.

That does not influence the copyright and the license. The copyright holder can of course change the license (as with DaDaBIK in June 2012). The license of the software also determines whether derivatives are allowed and can be commercial or not.

  • Hmm, I got it, so can I sell a product which is a modified version of an open-source? – Ruban Savvy Dec 11 '13 at 7:20
  • Not always. You really have to read the license under which the software is supplied, or search for an overview of licenses that explains it. – Zelda Dec 11 '13 at 7:25
  • @Ruban Savvy that depends on what license the code you are modifying has. – casey Dec 11 '13 at 7:26
  • so which license has the right to sell and which doesn't? – Ruban Savvy Dec 11 '13 at 7:28
  • 2
    You can /always/ sell, but most open source licenses require you to also offer to make the source freely available on request if you do so. – Shadur Dec 11 '13 at 7:55

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