Free software (free referring to freedom, not price) is software which can be used, copied, redistributed, and whose source code can be viewed, modified, and also redistributed.
"Free software" is not a subtopic of software patents. Development and distribution of all types of software carry the risk of patent infringement. The reason these two topics often appear together is that, firstly, the free software community is very active and vocal in campaigning against software patents, and secondly, software patents threaten a general freedom that free software users value: the freedom to participate in software development.
The term open source is a near-synonym. Patents restrict the freedom that users and developers have when dealing with software. Patents don't affect "openness", so en.swpat.org mostly uses the term "free software".
 Why free software groups should be involved
The free software movement says that everyone should be allowed to modify and redistribute the software they use. Software patents can directly block these freedoms, and can indirectly interfere with them because they generally add legal risks and costs to software development and distribution.
 How patents affect free software
 Advantages of free software faced with patents
- The development models are more distributed, so there's often no single big company behind a software package. This means there are fewer tempting targets for patent trolls
- If a patent holder makes a threat, anyone can remove that one feature from free software packages. The patent holder could still sue for past damages, but could not force the package to be entirely removed from the market, and the continued use of that patented idea is a decision that can be made by the users, not by making a deal with a single distributor.
- Distributing source code (which is possible for free software) carries less patent risk than distributing executable binaries, according to SFLC, since "source code, like the patent disclosures themselves, teaches how the invention works, rather than being the invention [...and...] courts may find source code to be speech".
 Disadvantages of free software faced with patents
- Many patent licensing agreements are structured in a way that excludes free software. If there is a per-copy fee, even if the amount is minuscule, there's no way to comply with this requirement because distributors can't know how many copies the users will make.
 Patent promises in 2005
- (See also: Blanket patent licences and promises)
IBM promised, for 500 of its patents, not to use them against free software.
 Related pages on en.swpat.org
- Free software distributors paying patent tax
- Free software projects harmed by software patents
- Vulnerable free software with shielded binaries
- Fake representatives of free software
- Harm to standards (examples include OpenGL 3, MPEG video formats, and GIF)
- Patent clauses in software licences
- passive threats - a common way that free software is "targeted"
- Patent promises - many of which are somewhat focussed on free software
- Novell-Microsoft patent deals
- Richard Stallman
- Free Software Foundation
- Breaks software distribution methods
- Free software exception - make just free software safe from patents??
- FRAND - discrimination via "Reasonable, and non-discriminatory" terms
- LiMux - project to migrate Munich city to GNU/Linux
- The Free Software Definition, gnu.org
- Software patents and free software, Wikipedia
- CALIU: Patents Threathen Free Software
- Operating systems will be developed by lawyers not programmers, 2006, FTI South Africa
- Microsoft seeks $50 per copy of Xandros GNU/Linux, 15 June 2009 (plus itWire coverage)
- "Effects of Software Patents on Free/Open Source/User Innovation", slides / video (works with Gnash)
- FSF's amicus brief for the 2009 Supreme Court case, contains details of how free software is important and how it's affected
- Patents - Why Free/Open Source Software Might Have Less to Fear than Non-Free Software, September 2004, by Dan Ravicher
- (See also: Harm with neither litigation nor threats)
- A 2004 patent deal regarding StarOffice/OpenOffice.org, signed with Sun Microsystems
- Patents as a threat to Free and Open Source Software, April 2010, by Florian Mueller
- Considerations For FLOSS Hackers About Oracle vs. Google, 16 Aug 2010, by Bradley Kuhn
- 4 ways open source [free software] protects you against software patents, 8 Nov 2013, Simon Phipps
 Pages from GNU/Linux distributions
- Ubuntu's patent policy
- Fedora's software patent information page
- Debian Position on Software Patents
This wiki is part of the End Software Patents (ESP) campaign (donate). For more information, see: