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Let's Encrypt vs ZeroSSL

How Let's Encrypt and ZeroSSL differ on deployment, pricing, openness and what each is actually built for.

Let's EncryptZeroSSL
TypePublic CA (free)Public CA (freemium)
DeploymentSaaS (ACME)SaaS (ACME)
How it worksIssues domain-validated TLS certificates at no cost, exclusively through the ACME protocol. Short 90-day lifetimes force automation, which is the point: renewal is a cron job, not a calendar reminder.Issues DV certificates over ACME like Let’s Encrypt, plus a browser console for teams that would rather click than script. Paid plans from $9.99/month add multi-domain certificates, a management console and support. Owned by HID Global, part of ASSA ABLOY.
Pricing*FreeFree tier; paid from $9.99/mo
Free tierYesYes
Open sourceBoulder (MPL-2.0)—
ComplianceWebTrust, CA/B ForumWebTrust, CA/B Forum
Best forPublic web TLS on anything you can automateACME with a UI and a support path

Let's Encrypt

  • Free and genuinely unlimited in practice
  • ACME everywhere — client support is universal
  • Short lifetimes push good automation hygiene
  • Domain validation only — no OV or EV
  • No support contract to escalate to

ZeroSSL

  • Drop-in ACME alternative — useful as a second issuer
  • Web console for non-automated workflows
  • Paid support exists, unlike Let’s Encrypt
  • Free tier is rate-limited and nagged
  • Much younger and smaller than the incumbents

Bottom line

Choose Let's Encrypt for public web tls on anything you can automate. Choose ZeroSSL for acme with a ui and a support path.

* Indicative list pricing (vendor documentation and public pricing pages, August 2026).