swi-prolog.org
SWI-Prolog
Last scanned Jul 27, 2026, 9:43 AM · 1 view
Overall score
Fair
Summary
This website uses Nginx hosted on Fastly behind Fastly CDN. SEO is fair (50/100) and accessibility is good (75/100). Security scores good (85/100) and performance excellent (90/100). Top issue: Missing meta description.
- United States
- Hosted on Fastly
Top issues to fix
11 issues found · 3 high priority
Missing meta description
SEOAdd a ~150-character meta description to control your search-result snippet and lift click-through rate.
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 viewport meta tag
AccessibilityAdd <meta name="viewport" content="width=device-width, initial-scale=1"> — without it the site is broken on mobile.
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.
+5 more issues — details in the sections below.
SEO
7 issue(s) found
Performance
1.61 s
Security
HTTPS & header checks
Accessibility
3 issue(s) found
Organization
Company details published in this site's own structured data.
Meta tags
- Title
- SWI-Prolog
- Description
- Canonical
- Language
- Charset
- UTF-8
- Viewport
- Robots meta
- Manifest
Technologies
Detected frameworks, languages, and tools.
Hosting & CDN
DNS records
| Type | Value |
|---|---|
| A |
|
| AAAA |
|
| MX | — |
| TXT | — |
| NS | — |
| CAA | — |
| CNAME |
|
| IPv6 support | Yes |
TLS / SSL certificate
- Version
- TLS 1.2
- Issuer
- GlobalSign nv-sa
- Subject
- www.swi-prolog.org
- Valid from
- Nov 10, 2025
- Valid to
- Dec 12, 2026
- Days until expiry
- 138
- SAN domains
- www.swi-prolog.org
Security headers
- Strict-Transport-SecurityEnabled
- Content-Security-PolicyEnabled
- X-Frame-OptionsMissing
- X-Content-Type-OptionsMissing
- Referrer-PolicyMissing
- Permissions-PolicyMissing
Compression: none · 0 cookie(s) observed
Content & assets
Headings
H1 0 · H2 0 · H3 0
Links
45 internal · 17 external · 0 broken
Images
16 total · 0 missing alt
Scripts / Styles
6 scripts · 5 stylesheets
JS / CSS size
358 KB · 53.9 KB
Page size
10.4 KB
Robots.txt & Sitemap
- robots.txt
- Not found
- Disallow rules
- 0
- sitemap.xml
- Not found
- URLs in sitemap
- 0
SEO issues
- Missing meta description
- Missing canonical link
- No H1 heading found
- No structured data (JSON-LD) found
- Missing OpenGraph tags
- robots.txt not found
- sitemap.xml not found
Accessibility issues
- No H1 heading found
- Missing <html lang> attribute
- Missing viewport meta tag
Scan details
- Requested URL
- https://swi-prolog.org
- Final URL
- https://www.swi-prolog.org/
- HTTP status
- 200
- HTTP version
- HTTP/2
- Response time
- 1.61 s
- HTML size
- 10.4 KB
- Redirect chain
- https://swi-prolog.org → https://www.swi-prolog.org/
See something wrong on this report? Request a correction
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Frequently asked questions
- What technology does swi-prolog.org use?
- swi-prolog.org is built with jQuery, Nginx.
- Is swi-prolog.org secure (HTTPS)?
- Yes. swi-prolog.org uses TLS 1.2 with a certificate issued by GlobalSign nv-sa, valid until Dec 12, 2026.
- Who hosts swi-prolog.org?
- swi-prolog.org is hosted on Fastly, behind Fastly CDN.
- What is swi-prolog.org's SEO score?
- swi-prolog.org scored 50/100 for SEO in the latest analysis (fair).
- What is swi-prolog.org's overall website score?
- swi-prolog.org has an overall SiteGraph score of 74/100, combining SEO, performance, security, and accessibility.
OpenGraph & Twitter Card
OpenGraph
Twitter Card