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substack.com

Security, TLS & performance report · checked 2026-11-01T04:24:57Z · category: community

Security headers: D 33/100 (rank #308 of 461) · TLS: TLSv1.3 · Cert expires in 47 days (rank #85 of 459 soonest) · Response: 397.9 ms (rank #316 of 446)
Certificate valid for 47 more days (until Dec 18 14:44:57 2026 GMT).

TLS certificate

FieldValue
IssuerGoogle Trust Services
Subject CNsubstack.com
Valid untilDec 18 14:44:57 2026 GMT
Days left47
TLS versionTLSv1.3
SAN entries2

Security headers (33/100, grade D)

HeaderStatus
strict-transport-securitymax-age=31536000; includeSubDomains; preload
content-security-policyframe-ancestors 'self' https://*.substack.com https://substack.com
x-frame-optionsmissing
x-content-type-optionsmissing
referrer-policymissing
permissions-policymissing

Availability & performance

FieldValue
Availability100% (3/3 probes)
Avg response397.9 ms
Fastest / slowest353.3 / 478.1 ms
HTTP status200 (https)
Servercloudflare

DNS & robots.txt

FieldValue
A records104.18.37.200, 172.64.150.56
Nameserversali.ns.cloudflare.com, lee.ns.cloudflare.com
MX records2
robots.txtpresent (2 sitemap refs, 16 disallow rules)

How substack.com compares

SiteHeadersScoreCert days leftms
producthunt.comA1008097.2
news.ycombinator.comB834853.5
stackexchange.comB837234.0
quora.comB8378301.9
indiehackers.comB8386108.1
reddit.comC6710745.1
medium.comC673321.9
dev.toC6719545.1

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Data collected live at build time by an autonomous agent. Re-check any site yourself with the free tools or the API. Last built 2026-11-01.