nbviewer.org
nbviewer
Last scanned Aug 24, 2026, 1:23 PM
Overall score
Fair
Summary
This website uses Plausible Analytics hosted on Fastly behind Fastly CDN. SEO is fair (65/100) and accessibility is fair (70/100). Security scores good (75/100) and performance excellent (100/100). Top issue: Missing meta description.
- United States
- Hosted on Fastly
Top issues to fix
10 issues found · 3 high priority
Missing Content-Security-Policy header
SecurityAdd a CSP to control which sources can run scripts — the strongest single defense against XSS.
Missing meta description
SEOAdd a ~150-character meta description to control your search-result snippet and lift click-through rate.
Over half of images are missing alt text
AccessibilityAdd alt attributes to images — screen readers depend on them, and they help image SEO.
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.
+4 more issues — details in the sections below.
SEO
5 issue(s) found
Performance
2 ms
Security
HTTPS & header checks
Accessibility
1 issue(s) found
Meta tags
- Title
- nbviewer
- Description
- Canonical
- Language
- en
- Charset
- utf-8
- Viewport
- width=device-width, initial-scale=1.0
- Robots meta
- noindex,nofollow
- Manifest
Technologies
Detected frameworks, languages, and tools.
Hosting & CDN
DNS records
| Type | Value |
|---|---|
| A |
|
| AAAA | — |
| MX | — |
| TXT | — |
| NS |
|
| CAA | — |
| CNAME | — |
| IPv6 support | No |
TLS / SSL certificate
- Version
- TLS 1.3
- Issuer
- Let's Encrypt
- Subject
- nbviewer.org
- Valid from
- Jul 13, 2026
- Valid to
- Oct 11, 2026
- Days until expiry
- 47
- SAN domains
- nbviewer.org
Security headers
- Strict-Transport-SecurityEnabled
- Content-Security-PolicyMissing
- X-Frame-OptionsMissing
- X-Content-Type-OptionsMissing
- Referrer-PolicyMissing
- Permissions-PolicyMissing
Compression: none · 0 cookie(s) observed
Content & assets
Headings
H1 1 · H2 1 · H3 3
Links
13 internal · 4 external · 13 broken
Images
12 total · 12 missing alt
Scripts / Styles
9 scripts · 3 stylesheets
JS / CSS size
741 B · 26 B
Page size
26 B
Robots.txt & Sitemap
- robots.txt
- Found
- Disallow rules
- 0
- sitemap.xml
- Not found
- URLs in sitemap
- 0
SEO issues
- Missing meta description
- Missing canonical link
- No structured data (JSON-LD) found
- Missing OpenGraph tags
- sitemap.xml not found
Accessibility issues
- Over half of images are missing alt text
Scan details
- Requested URL
- https://nbviewer.org
- Final URL
- https://nbviewer.org
- HTTP status
- 429
- HTTP version
- HTTP/2
- Response time
- 2 ms
- HTML size
- 26 B
- Redirect chain
- https://nbviewer.org
See something wrong on this report? Request a correction
Related websites
Same technology stack
noc.org
CDN & WAF for Hosts and MSPs | NOC.org
pushoperations.com
Push | #1 Payroll, HR and Workforce Management
goodgoodgood.co
Good Good Good | Good News & Hopeful Progress
dmnews.com
Direct Message News — Clarity and Insight in a Noisy World
brownbrothers.io
Home - Brown Brothers Media
42lolita.com
42Lolita - Online Lolita and Ouji Fashion Store
Same hosting provider
saltoks.com
Salto KS | Salto
fhinck.com
Fhinck — Task Mining + Agentes de IA | AI First
litera.com
Litera | Legal Technology Solutions
vovici.com
Survey Management Software | Verint
dvsa.gov.uk
Driver and Vehicle Standards Agency - GOV.UK
gapseat.in
GapSeat | IRCTC Chart Vacancy & Vacant Train Seats
Frequently asked questions
- What technology does nbviewer.org use?
- nbviewer.org is built with jQuery, Plausible Analytics.
- Is nbviewer.org secure (HTTPS)?
- Yes. nbviewer.org uses TLS 1.3 with a certificate issued by Let's Encrypt, valid until Oct 11, 2026.
- Who hosts nbviewer.org?
- nbviewer.org is hosted on Fastly, behind Fastly CDN.
- What is nbviewer.org's SEO score?
- nbviewer.org scored 65/100 for SEO in the latest analysis (fair).
- What is nbviewer.org's overall website score?
- nbviewer.org has an overall SiteGraph score of 77/100, combining SEO, performance, security, and accessibility.
OpenGraph & Twitter Card
OpenGraph
Twitter Card