Certainly vs ZeroSSL

ZeroSSL is used by more websites in our catalog: 776 use Certainly and 2,425 use ZeroSSL.

Certainly sites have the higher median Ahrefs Domain Rating (Certainly: 63, ZeroSSL: 23).

Between 2026-06 and 2026-07, Certainly went from 0.12% to 0.09% of all tracked sites, while ZeroSSL went from 0.29% to 0.28%. ZeroSSL is gaining ground faster in our index.

No. A site runs a single SSL certificate authority, so Certainly and ZeroSSL are mutually exclusive.

Adoption is counted from Site Stats Database's own crawl; Domain Rating comes from Ahrefs and traffic from DataForSEO. Figures reflect the sites we track and refresh at least monthly.