Quick verdict
Choose Let's Encrypt if you want the simplest, pure free DV solution with no setup. Choose ZeroSSL if you need OV/EV, a REST API or support — and can live with EAB setup. Both are equally secure and equally trusted.
Comparison
| Let's Encrypt | ZeroSSL | |
|---|---|---|
| Price (DV) | Free | Free (limited) + paid |
| ACME | Yes, no EAB | Yes, requires EAB |
| OV/EV | No | Yes (paid) |
| REST API | No | Yes |
| Support SLA | No | Yes (paid) |
| Wildcard | Yes (DNS-01) | Yes |
Where Let's Encrypt wins
Simplicity and ubiquity. No EAB, supported by virtually every ACME client, and a pure non-profit model. For DV on public web it is hard to beat. Read more in Let's Encrypt explained.
Where ZeroSSL wins
Breadth. If you need OV/EV, programmatic control via an API, or a support line, ZeroSSL covers it within the same ACME flow. Details in ZeroSSL explained.
How CertControl helps
You do not have to choose once and for all. CertControl's ACME server can relay to both, and CertControl monitors all certificates together — so you can freely mix CAs and still have one overview of expiry. See also best free SSL providers.
Frequently asked questions
Is Let's Encrypt or ZeroSSL more secure?
They are equally secure and equally trusted. The difference is features (OV/EV, API, support) and setup (ZeroSSL requires EAB), not security.
Why does ZeroSSL require EAB but Let's Encrypt does not?
ZeroSSL ties the ACME account to a ZeroSSL account via EAB. Let's Encrypt requires no prior registration to use ACME.
Can I use both?
Yes. Many organisations mix CAs. With an ACME server and unified monitoring you can use the best-suited CA per need.