The crt.sh code is all open on GitHub, so can be hosted yourself. Last I checked a few months ago, the main ‘certificates’ table and indexes etc was close to 20

The crt.sh code is all open on GitHub, so can be hosted yourself. Last I checked a few months ago, the main ‘certificates’ table and indexes etc was close to 20TB, and there’s more than just that. It’s big, but has everything. A slimmed down database of just some lightweight info on the certs and issuer (notBefore, not after, SANs, serials etc) runs maybe a TB in bigquery.