A factual comparison of the major CAs — not affiliate-driven, and separate from our Buy a Certificate page. Pricing changes often enough that we've left it out deliberately; check each CA's own site for current numbers.
| CA | Validation tiers | Target market | Warranty scale | Free automated option? |
| DigiCert | DV, OV, EV | Enterprise, regulated industries | Highest of the paid CAs — commonly cited in the seven-figure range | No |
| Sectigo (formerly Comodo) | DV, OV, EV | Wide range, budget to enterprise | Wide range depending on tier — from low four figures up to seven figures | No (but co-founded the CA/Browser Forum) |
| GlobalSign | DV, OV, EV | Enterprise, IoT/PKI at scale | Comparable to DigiCert's tier | No |
| Let's Encrypt | DV only | Everyone — the default for automated issuance | None (free tier has no warranty) | Yes — pioneered free ACME issuance |
| ZeroSSL | DV only | Developers wanting a dashboard/API on the free tier | None | Yes, plus a paid tier with dashboard/API access |
| Buypass | DV only | Anyone wanting a longer free-tier validity window | None | Yes — 180-day validity, longer than the others' 90-day default |
DigiCert and GlobalSign carry particular weight in enterprise procurement, compliance audits, and financial-sector vendor qualification — when a large company buys a certificate, finance logs the vendor and legal signs off on supplier qualifications, and an established enterprise CA's name on that paperwork can matter independently of the certificate's technical properties. For an individual site or small business, this consideration is close to irrelevant; for a regulated enterprise, it can be a genuine procurement requirement.
A CA's warranty is a commercial promise to pay up to a stated amount if a CA's own error (a key compromise leading to a fraudulent certificate, for instance) causes measurable loss. These are rarely invoked in practice, but the scale differs meaningfully: DigiCert and GlobalSign sit at the high end, Sectigo spans a wide range depending on the specific product tier, and free CAs carry no warranty at all. This matters most in finance, healthcare, and other liability-sensitive industries where the number itself gets scrutinized during vendor review.
Let's Encrypt, ZeroSSL, and Buypass all issue free, ACME-automated DV certificates using the identical underlying protocol — see our dedicated comparison for what actually differs between the three. None of the enterprise-tier CAs (DigiCert, Sectigo, GlobalSign) offer a free automated tier — their business model is built around OV/EV validation, warranty backing, and enterprise support contracts instead.
If you're specifically looking to display a verified brand logo in supporting email clients via BIMI, only three CAs are currently authorized to issue the required Verified Mark Certificate: DigiCert, Sectigo, and GlobalSign. Entrust exited the public CA business in 2025, selling it to Sectigo — a detail worth knowing if you come across an older guide that still lists Entrust as an option.
For a typical website with no specific enterprise procurement or regulatory requirement, a free automated CA (see our comparison of the three) covers the need entirely — the encryption is identical to any paid certificate. Reach for a paid enterprise CA specifically when you have a documented reason: a compliance requirement, a warranty your legal or finance team specifically wants on file, or genuine need for the OV/EV validation depth those tiers provide.
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