ZeroSSL issued 32 of the 8,208 certificates we observed on popular sites in November 2026.
Days between notBefore and notAfter of the leaf certificate.
On sites using ZeroSSL (accent) and all sites (grey).
Issuer organisation names seen in these certificates: ZeroSSL GmbH (32).
ZeroSSL issues certificates through the ACME protocol, so they are usually renewed automatically by a client such as Certbot, which explains short validity periods.
6.2% of the domains using ZeroSSL publish a CAA record (all sites: 20.7%). A CAA record names the CAs allowed to issue for the domain; any other CA must refuse.
CA site: https://zerossl.com/
Check one yourself:
Source: our own scan of November 2026 (2026-11-11), 9,971 of the top 10,000 domains of the Tranco list Y895G that answered in DNS. Method and data.