Substack SSL certificate status
Valid — 89 days until expiry(substack.com)
This page shows the Substack SSL certificate as served by substack.com, read from a live TLS handshake by an independent CertPost probe and rechecked hourly: expiry, issuer, hostname coverage, the full chain, and the negotiated protocol.
Last checked 2026-09-20 07:44 UTC. CertPost is not affiliated with Substack.
Certificate details
Hostnames this certificate covers
substack.com, *.substack.com
Certificate chain as served
Common questions
Is the Substack SSL certificate expired?
At the last check, the certificate substack.com serves was within its validity period. It expires on 2026-12-18, 89 days from that check.
When does the Substack SSL certificate expire?
The certificate substack.com is currently serving expires on 2026-12-18 (89 days from the last check). Large services rotate certificates long before that date.
Who issued the Substack SSL certificate?
The certificate was issued by WE1.
How is this checked?
A CertPost probe opens a real TLS connection to substack.com on port 443 and reads the certificate the server presents, the same way a browser does. The result is cached and refreshed hourly.
Substack rotates certificates without downtime. Your own domains are the ones that expire quietly — watch 3 free, no card.
Monitor your certificatesOr run a one-off check with the free SSL checker.