eprint.iacr.org has no institutional requirement, but it does have minimal standards. It takes a few days for them to review. It's not a real peer review, but t

eprint.iacr.org has no institutional requirement, but it does have minimal standards. It takes a few days for them to review. It's not a real peer review, but they check that you don't just publish gibberish or spam or something obviously wrong. (I have published there without an affiliation to a research institution.)