Free SSL Certificate Alternatives to Let's Encrypt: ZeroSSL, Buypass & Google Trust Services

Let's Encrypt has been the default choice for free SSL certificates since 2016 — and for good reason. But it is not the only option. Whether you are hitting rate limits, need a longer validity period, want a backup CA in case Let's Encrypt has an outage, or simply want to understand what else is available, this guide covers every major free SSL certificate authority in 2026.

Why You Might Need a Let's Encrypt Alternative

Let's Encrypt is reliable and widely trusted, but there are real situations where an alternative is useful:

• Rate limits. Let's Encrypt allows a maximum of 50 certificates per registered domain per week. If you manage dozens of subdomains on a single domain, you can hit this limit.
• 90-day validity. Let's Encrypt certificates expire every 90 days by design. While auto-renewal handles this automatically in most setups, some legacy systems or clients prefer longer validity periods.
• Redundancy. If Let's Encrypt infrastructure has an outage — which has happened historically — having a secondary CA configured means your renewals do not fail.
• cPanel AutoSSL compatibility. cPanel supports multiple SSL providers natively, including Sectigo (formerly Comodo) and Let's Encrypt. ZeroSSL can also be configured via ACME.
• Wildcard certificates via DNS. All major free CAs now support wildcard certificates, but the validation method and tooling differ.

The Major Free SSL Certificate Authorities in 2026

1. ZeroSSL

ZeroSSL is operated by Stack Holdings and is one of the most mature Let's Encrypt alternatives available today. It uses the same ACME protocol, meaning existing automation tools like acme.sh and Certbot work with it out of the box.

Key details:

• Certificate validity: 90 days
• Rate limits: 3 free certificates per month via web dashboard; unlimited via ACME API
• Wildcard support: Yes (via DNS-01 challenge)
• ACME support: Yes (same tooling as Let's Encrypt)
• Web dashboard: Yes — useful for manual issuance without CLI tools
• Trusted by: All major browsers and operating systems

ZeroSSL is particularly useful if you need a web-based interface to issue certificates without server access — for example, if you are managing a cPanel account without SSH.

How to use ZeroSSL with acme.sh:

# Register a ZeroSSL account
acme.sh --register-account -m [email protected] --server zerossl

# Issue a certificate
acme.sh --issue -d example.com --webroot /home/user/public_html \
  --server zerossl

# Issue a wildcard certificate (DNS validation required)
acme.sh --issue -d "*.example.com" --dns dns_cf \
  --server zerossl

2. Buypass Go SSL

Buypass is a Norwegian CA that offers free 180-day certificates — twice as long as Let's Encrypt. This is one of the most significant advantages of Buypass: fewer renewals per year means less operational overhead.

Key details:

• Certificate validity: 180 days (longest among free CAs)
• Rate limits: Generous; not publicly specified
• Wildcard support: Yes (via DNS-01 challenge)
• ACME support: Yes
• Web dashboard: No — ACME/CLI only
• Trusted by: All major browsers

# Issue a certificate via Buypass
acme.sh --issue -d example.com --webroot /home/user/public_html \
  --server https://api.buypass.com/acme/directory

# Wildcard via DNS
acme.sh --issue -d "*.example.com" --dns dns_cf \
  --server https://api.buypass.com/acme/directory

3. Google Trust Services (Google Public CA)

Google operates its own public Certificate Authority and offers free certificates via the ACME protocol. To use it, you need a Google Cloud account (free tier is sufficient — billing does not need to be enabled for ACME certificate issuance).

Key details:

• Certificate validity: 90 days
• Rate limits: Not publicly specified; effectively high for ACME usage
• Wildcard support: Yes
• ACME support: Yes
• Requirement: Google Cloud project (free tier works)
• Trusted by: All major browsers (Google is a root CA)

Google Trust Services is backed by one of the most resilient infrastructure providers in the world. For production environments that need maximum uptime on certificate issuance, this is a strong choice.

# Get EAB credentials from Google Cloud Console
# IAM & Admin > Service Accounts > Keys

# Register with acme.sh using EAB
acme.sh --register-account \
  --server https://dv.acme-v02.api.pki.goog/directory \
  --eab-kid YOUR_EAB_KID \
  --eab-hmac-key YOUR_EAB_HMAC_KEY \
  -m [email protected]

# Issue certificate
acme.sh --issue -d example.com --webroot /home/user/public_html \
  --server https://dv.acme-v02.api.pki.goog/directory

4. SSL.com Free Tier

SSL.com is a commercial CA that offers a limited free tier for 90-day DV certificates. Their ACME endpoint is available, though documentation is less beginner-friendly than the others.

• Certificate validity: 90 days
• ACME support: Yes
• Web dashboard: Yes
• Best for: Users who want a commercial CA backing with a free option

Comparison Table

Here is a quick reference for choosing the right free CA for your situation:

CA                       Validity  Wildcard  ACME  Dashboard  Best For
─────────────────────────────────────────────────────────────────────────
Let's Encrypt            90 days   Yes       Yes   No         Default, high-volume
ZeroSSL                  90 days   Yes       Yes   Yes        Web UI, no-CLI users
Buypass Go SSL           180 days  Yes       Yes   No         Fewer renewals
Google Trust Services    90 days   Yes       Yes   No         Max uptime / infra
SSL.com Free             90 days   Yes       Yes   Yes        Commercial CA feel

Setting Up Multi-CA Failover with acme.sh

The most resilient setup is not to pick one CA — it is to configure a primary CA with automatic fallback to a secondary. Here is how to do that with acme.sh:

#!/bin/bash
# multi-ca-renew.sh — attempt renewal with fallback CA

DOMAIN="example.com"
PRIMARY_CA="letsencrypt"
FALLBACK_CA="zerossl"
WEBROOT="/home/user/public_html"

# Try primary CA
acme.sh --renew -d "$DOMAIN" --server "$PRIMARY_CA" && exit 0

echo "Primary CA failed. Trying fallback: $FALLBACK_CA"

# Re-issue from fallback CA
acme.sh --issue --force -d "$DOMAIN" \
  --webroot "$WEBROOT" \
  --server "$FALLBACK_CA" && exit 0

echo "ERROR: Both CAs failed. Manual intervention required."
exit 1

Add this script to a cron job to run a few days before your certificate expires:

# Run renewal script 14 days before expiry, daily check
0 3 * * * /home/user/scripts/multi-ca-renew.sh >> /var/log/ssl-renew.log 2>&1

Installing SSL from Alternative CAs on cPanel

Once you have obtained a certificate from any of the above CAs, installing it on cPanel is the same process regardless of which CA issued it:

1. Log in to cPanel and navigate to Security → SSL/TLS
2. Click Manage SSL Sites
3. Select your domain from the dropdown
4. Paste your certificate files into the respective fields:
   • Certificate (CRT): the .crt file content
   • Private Key (KEY): the .key file content
   • Certificate Authority Bundle (CABUNDLE): the CA chain file
5. Click Install Certificate

If you are using acme.sh, certificate files are stored in ~/.acme.sh/example.com/ with extensions .cer (certificate), .key (private key), and ca.cer (CA chain).

Post-Installation Verification

After installing any SSL certificate, verify it is working correctly:

• Visit https://www.ssllabs.com/ssltest/ and enter your domain — you should get an A or A+ rating with a valid certificate chain.
• Check certificate details in your browser: click the padlock icon, view certificate, and confirm the issuer matches the CA you used.
• Test certificate expiry and chain validity with: openssl s_client -connect example.com:443 -showcerts
• Check that your auto-renewal cron job is active: crontab -l | grep acme

Conclusion

Let's Encrypt is still an excellent default, but it should not be the only SSL tool in your toolkit. ZeroSSL offers a web interface for non-CLI setups, Buypass provides longer 180-day certificates to reduce renewal frequency, and Google Trust Services offers infrastructure-grade reliability. Using a multi-CA strategy with acme.sh adds resilience to your SSL setup at no extra cost.

For cPanel users, the installation process is the same regardless of which CA issued the certificate — the value of these alternatives is in the issuance process and redundancy, not in how the certificate is installed.