Uncovering Cicada Wiki

The best.

Link: http://uncovering-cicada.wikia.com/

CicadaSolvers Reddit and Discord

Reddit: https://www.reddit.com/r/CicadaSolvers/

Discord: https://discord.com/channels/572330844056715284/

cicada.gq

Various tools running in your browser.

Link: https://cicada.gq/

cicada3301.boards.net

Ideas.

Link: https://cicada3301.boards.net/

#cicadasolvers on freenode

Link: http://webchat.freenode.net/?channels=cicadasolvers

IRC chat. Defunct?

Max Bernstein's Cicada 3301 page

Link: http://bernsteinbear.com/blog/cicada

A page on Max Bernstein's blog.

clevcode.org/cicada-3301

Link: http://www.clevcode.org/cicada-3301/

on Github

Bibanon

Link: https://github.com/bibanon/bibanon/wiki/Cicada-3301-wiki

Michel Oosterhof

Links: https://github.com/micheloosterhof/cicada-2014 and https://github.com/micheloosterhof/cicada-2016

A good repo.

rtkd/idkfa and rtkd/iddqd

Link: https://github.com/rtkd/idkfa and https://github.com/rtkd/iddqd