Open Source Licensing

Your choices and what works

February 2017


  • Not a lawyer
  • Ask questions, interrupt, correct me
  • Have you had to choose a license?

1970s: How to make money from software

The way it was characterized politically, you had copyright, which is what the big companies use to lock everything up; you had copyleft, which is free software's way of making sure they can't lock it up; and then Berkeley had what we called ‘copycenter’, which is ‘take it down to the copy center and make as many copies as you want.’
- Kirk McKusick, BSD author

Permissive licensing - Copycenter

  • Do whatever you want, with very few requirements
  • BSD - distribute, modify and use, just cite
  • MIT - no restrictions, including sublicensing, just cite
  • Apache - extensive list of common rights granted, patent license if you don't sue, just cite
  • Boost - list of common rights granted, cite in source but not binary


  • Free to copy and redistribute, but make the source and your modifications available in return
  • GNU GPL - have to include source when you redistribute, server loophole, dynamic linking allowed?
  • LGPL - GPL compromise for libraries
  • MPL - have to include source for individual files, patent license if you don't sue
  • CDDL - MPL with different legalese
  • AGPL - closes server loophole for GPL

What works? Open Core

  • Business models matter: IBM, Red Hat, Google
  • Ties proprietary to open source
  • The most successful open source projects use it: Android, llvm, Chrome, linux?
  • Copyleft business model - Dual licensing
  • Permissive or weak copyleft - Proprietary modules
  • Huge for India


By danatic


An exposition of current open source licenses and the open core business model.

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