Pingdom tells you the site is up. Whether the certificate your visitors receive is valid is a different check.
Verified 19 Aug 2026
Pingdom is a capable uptime and synthetic monitor. If it already watches your sites, keep it.
Its SSL coverage rides on an HTTPS uptime check: switch the check to HTTPS and it warns you before the certificate expires — on the day by default, configurable up to a month ahead. That catches the simplest failure, a leaf certificate running out, and it uses one of your paid checks per site.
The failures that actually take TLS down are mostly not the leaf date:
• An intermediate above your certificate expires. The leaf is still valid, browsers still throw errors, and a days-until-expiry check stays green. This is what broke thousands of sites when the AddTrust root lapsed.
• Renewal succeeded on disk but the web server never reloaded, so the certificate on the wire is still the old one. Only a live handshake from outside sees it.
• A re-issue drops a SAN, or DNS points a name at the wrong host. The page still returns 200; browsers still warn.
• A certificate you did not issue appears for your domain — worth an alert the same day, not never.
• Mail and admin ports. SMTP on 465 and 587, IMAPS on 993, a panel on 8443 — each holds its own certificate, and an HTTP uptime check only looks at 443.
CertPost is built for that job. Every check opens a real TLS connection and validates the certificate your visitors actually receive: full chain including intermediates, hostname and SAN match, fingerprint-change detection, expiry — on any TLS port, over IPv4 and IPv6 — plus domain-registration expiry, Certificate Transparency issuance alerts, and DNS record drift.
Run both. Pingdom answers "is the site up and fast?". CertPost answers "is the certificate valid everywhere it is served, and will it stay that way?".
Three certificates are free forever, checked daily, every alert channel included, no card. Paid is a flat $29/month for unlimited certificates. Pingdom's plans are priced by the number of checks, so an SSL check competes with your uptime checks and the cost grows with every site you add.
The five-minute pairing:
1. Keep Pingdom pointed at your homepage for uptime and speed.
2. Sign up for CertPost free — no card.
3. Paste every hostname that terminates TLS: apex, www, API, and the mail and admin hosts with their ports (mail.example.com:465, imap.example.com:993, panel.example.com:8443). One per line.
4. Point both at the same alert channel.
Now Pingdom tells you the site is up, and CertPost tells you the certificate behind it is still the one your visitors should be getting.
Import your domain list in 2 minutes — 3 certificates free, no card.
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