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SGSiteGraph

ncatlab.org website report

nLab

Last scanned

Overall score

Great

Score profile

SEO55Performance100Security100Accessibility100
This siteAll scanned sites median

Top issues to fix

8 issues found · 1 high priority

  • Missing meta description

    SEO

    Add a ~150-character meta description to control your search-result snippet and lift click-through rate.

  • Missing canonical link

    SEO

    Add <link rel="canonical"> so search engines know which URL variant to index.

  • Multiple H1 headings found

    SEO

    Keep a single H1 per page and demote the others to H2/H3.

  • No structured data (JSON-LD) found

    SEO

    Add JSON-LD (Organization, Article, Product…) to become eligible for rich results.

  • Missing OpenGraph tags

    SEO

    Add og:title/og:description/og:image so shared links render a proper preview card.

  • robots.txt not found

    SEO

    Publish /robots.txt with a Sitemap: directive to guide crawlers.

+2 more issues — details in the sections below.

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

How it compares

ncatlab.org scores higher overall than 75% of the 163,243 sites we have scanned.

vs. All scanned sites

163,243 sites
Overall75th
SEO20th
Performance70th
Security95th
Accessibility80th

The dot is this site; the tick is the typical (median) score for the group. The number on the right is the percentile: the share of the group this site scores above.

Technology stack

ncatlab.org is built with Nginx.

Servers (1)

Hosting & DNS

Domain
ncatlab.org
IP address
ASN
IPv6
Not supported
HTTP
HTTP/1.1
0
A
0
AAAA
0
MX
0
NS
0
TXT
0
CAA
Show DNS record values

TXT record contents are not republished; only their count is shown.

Security

ncatlab.org uses TLS 1.3 with a certificate valid for 70 more days and sets 4 of 6 recommended security headers.

Security

Security headers4 of 6 set

  • HSTS
    Forces HTTPS
  • CSP
    Blocks injected scripts
  • X-Frame-Options
    Stops clickjacking
  • X-Content-Type
    Stops MIME sniffing
  • Referrer-Policy
    Limits URL leakage
  • Permissions-Policy
    Restricts browser features

TLS certificate

VerifiedTLS 1.3 · Let's Encrypt
Aug 5, 202670 days leftNov 3, 2026
Names covered
1
Cookies set
0

Email security

ncatlab.org scores B for email security, with SPF and DMARC policy “reject”.

B
75 / 100
  • SPFGood

    Rejects senders not listed (-all).

  • DMARCGood

    Forged mail is rejected; reports are collected.

  • MTA-STSNot set

    Not published; mail to this domain can be downgraded to plaintext.

  • BIMINot set

    Not published (optional).

Performance & carbon

ncatlab.org scores 100/100 for performance, with an estimated load time of 0.6 s. A visit emits an estimated 0.02 g of CO2 (grade A+).

Performance

Page weight

  • HTML 51.4 KB
  • JavaScript 1.6 KB
  • CSS 3.7 KB
Est. load
580 ms
Response
579 ms
Scripts / CSS
10 / 5

Carbon per visitA+

A+ABCDEF

0.02 g CO2 per uncached view

Estimate from the Sustainable Web Design model. HTML, JavaScript and CSS only; images, video and fonts are not measured. Treat it as a lower bound for comparing pages, not an audit.

SEO & accessibility

ncatlab.org scores 55/100 for SEO and 100/100 for accessibility, with 7 SEO issues to fix.

SEO
Accessibility

Heading structure

H12H29H32H40H50H60

2 H1s; one is the convention.

Image alt text

100%

0 images · 0 without alt text · 0 lazy-loaded

Links

  • Internal 259
  • External 18
  • Broken 10

SEO issues7

  • Missing meta description
  • Missing canonical link
  • Multiple H1 headings found
  • No structured data (JSON-LD) found
  • Missing OpenGraph tags
  • robots.txt not found
  • sitemap.xml not found

Accessibility issues0

No accessibility issues detected.

Technical details

Page metadata, social tags, crawl files and scan information.

Meta tags

Title
nLab
Description
Canonical
Language
en
Robots meta
index,follow

Open Graph & Twitter

og:title
og:type
twitter:card
twitter:title

Crawl files

robots.txt
Not found
Disallow rules
0
sitemap.xml
Not found
URLs in sitemap
0

Structured data

No JSON-LD types declared.

Microdata items
0
RDFa items
0

Scan

Final URL
https://ncatlab.org/nlab/show/HomePage
HTTP status
200
Redirects
https://ncatlab.org → https://ncatlab.org/nlab/show/HomePage
Scanned
Aug 24, 2026, 1:23 PM

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Frequently asked questions about ncatlab.org

What is ncatlab.org?
ncatlab.org is a website.
What technology does ncatlab.org use?
ncatlab.org is built with Nginx.
Is ncatlab.org secure?
ncatlab.org uses TLS 1.3 with a certificate valid for 70 more days and sets 4 of 6 recommended security headers.
Is ncatlab.org protected against email spoofing?
ncatlab.org scores B for email security, with SPF and DMARC policy “reject”.
How does ncatlab.org compare with similar sites?
ncatlab.org scores higher overall than 75% of the 163,243 sites we have scanned.
What is ncatlab.org's overall score?
ncatlab.org has an overall SiteGraph score of 87/100, combining SEO (55), performance (100), security (100) and accessibility (100).