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astralcodexten.com

Astral Codex Ten | Scott Alexander | Substack

Last scanned Jul 27, 2026, 10:43 AM · 1 view

91

Overall score

Excellent

Summary

P(A|B) = [P(A)*P(B|A)]/P(B), all the rest is commentary. This website uses Express hosted on Cloudflare behind Cloudflare CDN. SEO is excellent (100/100) and accessibility is excellent (100/100). Security scores good (85/100) and performance good (80/100).

P(A|B) = [P(A)*P(B|A)]/P(B), all the rest is commentary. Click to read Astral Codex Ten, by Scott Alexander, a Substack publication.

United States
Hosted on Cloudflare

Top issues to fix

2 issues found

  • Missing X-Content-Type-Options header

    Security

    Add X-Content-Type-Options: nosniff to stop MIME-sniffing attacks.

  • Missing X-Frame-Options header

    Security

    Add X-Frame-Options (or a CSP frame-ancestors rule) to prevent clickjacking via hidden iframes.

100

SEO

0 issue(s) found

80

Performance

827 ms

85

Security

HTTPS & header checks

100

Accessibility

0 issue(s) found

Not enough scan history yet to show a trend — check back after this site has been re-scanned a few more times.

Organization

Company details published in this site's own structured data.

P(A|B) = [P(A)*P(B|A)]/P(B), all the rest is commentary. Click to read Astral Codex Ten, by Scott Alexander, a Substack publication.

Meta tags

Title
Astral Codex Ten | Scott Alexander | Substack
Description
P(A|B) = [P(A)*P(B|A)]/P(B), all the rest is commentary. Click to read Astral Codex Ten, by Scott Alexander, a Substack publication.
Canonical
https://www.astralcodexten.com/
Language
en
Charset
utf-8
Viewport
width=device-width, initial-scale=1, maximum-scale=1, user-scalable=0, viewport-fit=cover
Robots meta
Manifest

OpenGraph & Twitter Card

OpenGraph

og:title
Astral Codex Ten | Scott Alexander | Substack
og:description
P(A|B) = [P(A)*P(B|A)]/P(B), all the rest is commentary. Click to read Astral Codex Ten, by Scott Alexander, a Substack publication.
og:type
article
og:url
https://www.astralcodexten.com/

Twitter Card

twitter:card
summary_large_image
twitter:title
Astral Codex Ten | Scott Alexander | Substack
twitter:description
P(A|B) = [P(A)*P(B|A)]/P(B), all the rest is commentary. Click to read Astral Codex Ten, by Scott Alexander, a Substack publication.

Technologies

Detected frameworks, languages, and tools.

Hosting & CDN

Hosting provider
Cloudflare
CDN provider
Cloudflare
IP address
104.18.36.24
ASN
AS13335 (CLOUDFLARENET - Cloudflare, Inc., US)

DNS records

TypeValue
A
  • 104.18.36.24
  • 172.64.151.232
AAAA
  • 2606:4700:4401::6812:2418
  • 2606:4700:4406::ac40:97e8
MX
TXT
NS
CAA
CNAME
  • target.substack-custom-domains.com
IPv6 supportYes

TLS / SSL certificate

Version
TLS 1.3
Issuer
Google Trust Services
Subject
www.astralcodexten.com
Valid from
Jul 14, 2026
Valid to
Oct 12, 2026
Days until expiry
77
SAN domains
www.astralcodexten.com

Security headers

  • Strict-Transport-SecurityEnabled
  • Content-Security-PolicyEnabled
  • X-Frame-OptionsMissing
  • X-Content-Type-OptionsMissing
  • Referrer-PolicyMissing
  • Permissions-PolicyMissing

Compression: gzip · 3 cookie(s) observed

Content & assets

Headings

H1 1 · H2 0 · H3 0

Links

14 internal · 24 external · 0 broken

Images

15 total · 0 missing alt

Scripts / Styles

171 scripts · 22 stylesheets

JS / CSS size

681 KB · 722 KB

Page size

372 KB

Robots.txt & Sitemap

robots.txt
Found
Disallow rules
15
sitemap.xml
Found
URLs in sitemap
1440

SEO issues

No SEO issues detected.

Accessibility issues

No accessibility issues detected.

Scan details

Requested URL
https://astralcodexten.com
Final URL
https://www.astralcodexten.com/
HTTP status
200
HTTP version
HTTP/2
Response time
820 ms
HTML size
372 KB
Redirect chain
https://astralcodexten.com → https://www.astralcodexten.com/

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Frequently asked questions

What technology does astralcodexten.com use?
astralcodexten.com is built with Express, Node.js, Google Analytics, Cloudflare Analytics, Google Ads.
Is astralcodexten.com secure (HTTPS)?
Yes. astralcodexten.com uses TLS 1.3 with a certificate issued by Google Trust Services, valid until Oct 12, 2026.
Who hosts astralcodexten.com?
astralcodexten.com is hosted on Cloudflare, behind Cloudflare CDN.
What is astralcodexten.com's SEO score?
astralcodexten.com scored 100/100 for SEO in the latest analysis (excellent).
What is astralcodexten.com's overall website score?
astralcodexten.com has an overall SiteGraph score of 91/100, combining SEO, performance, security, and accessibility.