cnx.org
OpenStax
Last scanned Jul 29, 2026, 7:00 PM · 7 views
Overall score
Fair
Summary
OpenStax offers free college textbooks for all types of students, making education accessible & affordable for everyone. This website uses Meta Pixel behind CloudFront CDN. SEO is fair (65/100) and accessibility is excellent (90/100). Security scores fair (65/100) and performance excellent (100/100). Top issue: Missing canonical link.
OpenStax offers free college textbooks for all types of students, making education accessible & affordable for everyone. Browse our list of available subjects!
Top issues to fix
9 issues found · 3 high priority
Missing Strict-Transport-Security header
SecurityAdd HSTS so browsers always use HTTPS — this closes the protocol-downgrade attack window.
Missing Content-Security-Policy header
SecurityAdd a CSP to control which sources can run scripts — the strongest single defense against XSS.
No H1 heading found
SEOAdd exactly one H1 describing the page's main topic — it anchors the document outline for search engines and screen readers.
Missing X-Content-Type-Options header
SecurityAdd X-Content-Type-Options: nosniff to stop MIME-sniffing attacks.
Missing X-Frame-Options header
SecurityAdd X-Frame-Options (or a CSP frame-ancestors rule) to prevent clickjacking via hidden iframes.
Missing canonical link
SEOAdd <link rel="canonical"> so search engines know which URL variant to index.
+3 more issues — details in the sections below.
SEO
5 issue(s) found
Performance
21 ms
Security
HTTPS & header checks
Accessibility
1 issue(s) found
Score history
-3 overall since Jul 22, 2026
- Overall
- 79
- SEO
- 65
- Security
- 65
- Performance
- 100
- Accessibility
- 90
Organization
Company details published in this site's own structured data.
OpenStax offers free college textbooks for all types of students, making education accessible & affordable for everyone. Browse our list of available subjects!
Meta tags
- Title
- OpenStax
- Description
- OpenStax offers free college textbooks for all types of students, making education accessible & affordable for everyone. Browse our list of available subjects!
- Canonical
- Language
- en-US
- Charset
- utf-8
- Viewport
- width=device-width,initial-scale=1,maximum-scale=5
- Robots meta
- Manifest
- https://openstax.org/dist/assets/manifest.webmanifest
Technologies
Detected frameworks, languages, and tools.
Hosting & CDN
- Hosting provider
- —
- CDN provider
- CloudFront
- IP address
- —
- ASN
- —
DNS records
| Type | Value |
|---|---|
| A | — |
| AAAA | — |
| MX | — |
| TXT | — |
| NS | — |
| CAA | — |
| CNAME | — |
| IPv6 support | No |
TLS / SSL certificate
- Version
- TLS 1.3
- Issuer
- Amazon
- Subject
- openstax.org
- Valid from
- Oct 12, 2025
- Valid to
- Nov 10, 2026
- Days until expiry
- 104
- SAN domains
- openstax.org, *.openstax.org
Security headers
- Strict-Transport-SecurityMissing
- Content-Security-PolicyMissing
- X-Frame-OptionsMissing
- X-Content-Type-OptionsMissing
- Referrer-PolicyMissing
- Permissions-PolicyMissing
Compression: gzip · 0 cookie(s) observed
Content & assets
Headings
H1 0 · H2 0 · H3 0
Links
0 internal · 0 external · 0 broken
Images
0 total · 0 missing alt
Scripts / Styles
6 scripts · 0 stylesheets
JS / CSS size
0 B · 0 B
Page size
12.1 KB
Robots.txt & Sitemap
- robots.txt
- Not found
- Disallow rules
- 0
- sitemap.xml
- Not found
- URLs in sitemap
- 0
SEO issues
- Missing canonical link
- No H1 heading found
- No structured data (JSON-LD) found
- robots.txt not found
- sitemap.xml not found
Accessibility issues
- No H1 heading found
Scan details
- Requested URL
- https://cnx.org
- Final URL
- https://openstax.org
- HTTP status
- 200
- HTTP version
- HTTP/2
- Response time
- 21 ms
- HTML size
- 12.1 KB
- Redirect chain
- https://cnx.org → https://openstax.org
See something wrong on this report? Request a correction
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Frequently asked questions
- What technology does cnx.org use?
- cnx.org is built with Meta Pixel.
- Is cnx.org secure (HTTPS)?
- Yes. cnx.org uses TLS 1.3 with a certificate issued by Amazon, valid until Nov 10, 2026.
- Who hosts cnx.org?
- Hosting provider information for cnx.org is not available yet.
- What is cnx.org's SEO score?
- cnx.org scored 65/100 for SEO in the latest analysis (fair).
- What is cnx.org's overall website score?
- cnx.org has an overall SiteGraph score of 79/100, combining SEO, performance, security, and accessibility.
- Has cnx.org's score changed over time?
- cnx.org's overall score has declined by 3 points (from 82 to 79) since Jul 22, 2026.
OpenGraph & Twitter Card
OpenGraph
Twitter Card