What is Sectigo?

Sectigo is a commercial certificate authority that issues TLS certificates across all the validation levels, from free domain-validated certificates to organisation and extended-validation ones. It was known as Comodo CA for years and rebranded to Sectigo in 2018, after the certificate business was separated from the rest of Comodo. Because of that history, its intermediates and older certificates still carry the Comodo name in places, which can be confusing when you read a chain.

As a commercial authority, Sectigo competes on the parts a free authority does not offer: organisation and extended validation, longer support relationships, warranties, and bundled products like code-signing and email certificates. For a plain domain-validated certificate on a website, the certificate a customer receives is technically the same kind of file a free authority issues; the difference is the vetting and the support around it.

Sectigo runs its own roots that ship in the major trust stores, so its certificates are trusted by browsers without any extra steps, the same as any established authority. When you see an issuer like "Sectigo RSA Domain Validation Secure Server CA" in a certificate chain, that is the intermediate doing the signing, and it must be served alongside your leaf for the chain to validate.

For an operator choosing between Sectigo and a free authority, the deciding factors are validation level and process, not trust. If you need an organisation or extended-validation certificate, or a support relationship and warranty, a commercial authority like Sectigo is the fit. If you need automated domain-validated certificates on a schedule, a free authority is usually simpler. Either way the resulting certificate is served and monitored the same, and its expiry is the thing to watch.