It's listed in https://choosealicense.com/appendix/

The point of the home page is to make it easy to choose a license, not to list every possible choice.

(I occasionally help maintain https://github.com/github/choosealicense.com which is the source for the site.)

Fun fact: at least one large company I worked with explicitly internally documented WTFPL-licensed software as unable to be merged into their codebase, because lawyers. Cf. MIT/BSD/Apache/ISC/CC-BY/CC0 that were all fine.

IBM's lawyers reportedly asked Poul-Henning Kamp "how much beer?" re: the Beer-ware unlicense[0].

[0]: http://edwards.dk/thesis.pdf (p. 120, 231)

WTFPL is not OSI-approved and so briefly held up containerd coming into CNCF.

https://github.com/chanezon/toml#about-this-fork

IANAL, this is not legal advice, etc.

If you disagree that the WTFPL is a useable license, how does forking & relicensing work? Changing the license requires having a license that allows you to do so to the new target license (or ownership of the copyright). But if our assumption is that we reject the WTFPL as a valid license, how can we simultaneously use it to relicense?

I.e., instead of a needing a legal debate about whether the WTFPL allows you to use the code, it would seem to me you trade that for a legal debate about whether the WTFPL allows you to re-license the code.

(At any rate, the upstream relicensed to MIT, and BurntSushi sought agreement from "major contributors, where I interpreted 'major' as '100 lines of code or more.'", so the entire thing appears moot.)

Yes, clearly you can't change the license of a project you don't have a valid license to.

Include Google:

https://opensource.google.com/docs/thirdparty/licenses/#bann...

Some of us rather like that unintended consequence of the WTFPL.

That may or may not hold up in court. Best to not use it if you actually want to release all copyrights.

This is potentially a concern for software licensees, but not the author of the work.

Absolutely true, but the reason someone licenses their software under an open source license at all is because they want it to be open source. Some developers may erraneously think this is a good open source license, when in fact it might not have the effect they intended.

It's not an OSI recognized license.