Is Substack SSL down right now?
This page answers whether Substack SSL is down by checking the certificate substack.com serves, live and from outside, rechecked every hour. Most "is it down" pages ping the homepage; a broken or expired certificate is a different failure, and it is the one this page watches.
Last checked 2026-09-20 07:44 UTC. CertPost is not affiliated with Substack.
Common questions
Is Substack SSL down right now?
No. At the last check the certificate substack.com serves was valid, and it expires on 2026-12-18. Substack SSL is up.
How does this page know if Substack SSL is down?
A CertPost probe opens a real TLS connection to substack.com on port 443, the same way a browser does, and reads the certificate. The result is cached and rechecked every hour, so this reflects the healthy state seen at the last check, not a guess.
Is this the same as Substack being down?
Not always. A site can be reachable while its certificate is broken, or down for reasons unrelated to SSL. This page measures only the certificate substack.com serves. For the full certificate detail, see the Substack certificate status page.
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