A little compilation since I get many questions about these.

ICAR (International Cognitive Ability Resource), cognitive items. Public domain but not open

This is probably the largest project of open cognitive ability/intelligence items. ICAR, cognitive items. Public domain (not copyrighted) but hidden away. Some key publications:

To get the items, one has to go to icar-project.com register, and then get approved. Although this doesn’t cost any money, it is a barrier.

Their website also hosts a very long list of other PDFs, mainly slides from conferences and unpublished papers. As of writing, Google finds 813 PDFs on the site.

Other cognitive items

Some papers:

Non-cognitive items

Some papers:

Worth mentioning