Any recommendation of a "default" license to use if you don't care too much about licensing will always carry strong opinions of whoever is recommending it. So, instead, here's a decision tree of good recommendations based on the two biggest decisions that factor in to choosing a license:
start
|
V
if I modify it, and give someone a
compiled binary of that, should I also
have to give (or offer) them the source?
| |
yes | | no
| V
| MIT/X11 license
| (alternatively,
| Apache 2.0, or
| 2- or 3-clause BSD)
V
is it a library
or a program?
/ \
library / `----, program
V \
can it be used by programs \
that DON'T give/offer the \
source with binaries? \
| \ \
yes | \ no V
V `-----------> GNU GPL
GNU LGPL (alternatively, GNU AGPL)
Whether or not you think the "default" choice to each question should be "yes" or "no" is something that people argue about plenty; whichever you choose, someone will tell you you chose wrong.
As for the "alternatives" in parenthesis at the leaves of the chart: if you don't care about licenses, the default is probably fine, but if someone told you that you should use one of the alternatives at that leaf, I wouldn't argue. (Apache 2.0 comes in over MIT if you care about patents, AGPL comes in over GPL if you care about SaaSS)
It's a good chart, but I'd add: is the source code meant to be an example/educational and/or is trivial[1]: cc0 - somewhere on the top right.
[1] by definition trivial code isn't copyrightable - but "trivial" is subjective. If you, as the author feel it is, might as well clearly signal that and use cc0.
As for the "alternatives" in parenthesis at the leaves of the chart: if you don't care about licenses, the default is probably fine, but if someone told you that you should use one of the alternatives at that leaf, I wouldn't argue. (Apache 2.0 comes in over MIT if you care about patents, AGPL comes in over GPL if you care about SaaSS)