CertFleet
SSL and HTTP uptime monitoring with live TLS probes and alerts
CertFleet monitors SSL certificates and HTTP uptime in one place. It opens a real TLS handshake on port 443, tracks Certificate Transparency for new issuances, and sends alerts at 30, 14, 7, and 1 day before expiry. You can configure HTTP checks with custom methods, paths, status codes, and body keywords. Notifications are sent via email, Slack, webhooks, or SMS. It is free forever for 10 SSL and 10 uptime monitors, with public status pages and a REST API available on paid plans.