The Shortest FOSS (Free / Open Source Software) License

Now and then, you may be wondering what is the shortest and simplest possible Open Source license.  Maybe you are contributing some Free Software to the world for your fun, glory and profit, and you want to save precious bytes in your project directory?

The Software Package Data Exchange® (SPDX®) publishes a list of (probably all) Open Source licenses. The page specifies license name, codename, full text, whether it's approved by Open Source Institute and whether it's recognized by the Free Software Foundation as Free/Libre license.

I was curious which one is the most terse, and I wrote a little Python script to scrape the data from SPDX page, parse it and save to CSV.

The script is here: spdx_licenses.py.

Here are the winners.

1. The shortest Open Source license is the diffmark license - it's only 17 words and 88 characters long, but it's neither FSF-approved nor OSI-approved. Personally, I love it. The credits for license text should probably go to Václav Bárta (http://www.mangrove.cz/diffmark/). Use it if you are brave. Quoting in full:

1. you can do what you want with it 2. I refuse any responsibility for the consequences

2. The shortest FSF-approved Open Source license is the FSF All Permissive License. It is 34 words, 224 characters long. Quote:

Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved. This file is offered as-is, without any warranty.

3. The shortest OSI-approved Open Source license is the Fair License. It is 36 words, 229 characters long. Quote:

<Copyright Information> Usage of the works is permitted provided that this instrument is retained with the works, so that any entity that uses the works is notified of this instrument. DISCLAIMER: THE WORKS ARE WITHOUT WARRANTY.

4. The shortest Open Source license which is both FSF-approved and OSI Approved is the ISC License. It is 128 words, 819 characters long. Use it to get your back covered against most lawyers. Quoting:

ISC License Copyright (c) 2004-2010 by Internet Systems Consortium, Inc. ("ISC") Copyright (c) 1995-2003 by Internet Software Consortium Permission to use, copy, modify, and /or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

You may also wonder about the losers. Unsurprisingly, one of the longest licenses is the famous GNU General Public License v3.0 (over 5650 words, 38000 characters) - but it's  beaten by the Adaptive Public License 1.0 which is over 7100 words, 52500 characters! Whoa - pretty long for a free software license.