swi-prolog.org

We performed a comprehensive analysis of swi-prolog.org on 2026-06-30. The website returned an HTTP 200 status code with a server response time of 9322ms. The page is served over HTTP/2 protocol with Gzip compression enabled, achieving approximately 60.0% size reduction. The total page weight is 10 KB, and the site is served behind a CDN (Content Delivery Network). The website uses a secure HTTPS connection with a valid SSL certificate issued by Let's Encrypt (DV type). The connection is encrypted using TLS 1.3 with the TLS_AES_256_GCM_SHA384 cipher suite and sha256WithRSAEncryption signature algorithm. The certificate covers 10 domain(s) (Subject Alternative Names) and expires on 2026-08-08, which is 39 days from now. The security headers analysis reveals a score of 40/100 (below average). The following security headers are properly configured: Content-Security-Policy and Strict-Transport-Security (HSTS). However, the site is missing X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and Permissions-Policy, which could expose the site and its users to cross-site scripting (XSS), clickjacking, and other web-based attacks. Our technology detection scan identified 2 technologies across 2 categories powering swi-prolog.org. The detected stack includes GitHub Pages and jQuery 3.6.0.. Based on our comprehensive analysis of domain age, SSL configuration, email authentication, security headers, and blacklist status, swi-prolog.org receives an overall trust score of 77/100, classified as "Likely Safe".

After conducting a thorough safety and legitimacy analysis, swi-prolog.org receives a trust score of 77/100, which places it in the "Likely Safe" category. This score is calculated by evaluating multiple factors including SSL certificate validity, domain registration history, email authentication protocols, security header configuration, and blacklist status across major threat intelligence databases. The analysis identified several positive trust signals: a valid HTTPS connection protecting data in transit, HSTS (HTTP Strict Transport Security) enforcement preventing protocol downgrade attacks, a valid SSL certificate issued by Let's Encrypt with 39 days until expiration, SPF (Sender Policy Framework) email authentication preventing email spoofing, DMARC email authentication with a none policy, DNSSEC providing authenticated DNS responses, and a well-established domain registered for over 24.6 years, indicating long-term commitment and legitimacy. Areas of concern include: no X-Frame-Options header, which could allow the site to be embedded in malicious iframes (clickjacking), missing Referrer-Policy, potentially leaking URL information to third parties, and the domain's WHOIS information is hidden behind a privacy service, making it harder to verify the owner's identity. While these issues don't necessarily indicate malicious intent, they represent areas where the website's security posture could be improved. We checked swi-prolog.org against 8 major blacklist databases including Google Safe Browsing, Phishtank, Urlhaus, Openphish, Dnsfilter, Spamhaus Dbl, Surbl, and Virustotal. The domain passed all 8 checks with a clean status, meaning it has not been flagged for phishing, malware distribution, spam, or other malicious activities by any of the tested threat intelligence providers. The domain is registered through Key-Systems GmbH, with a registration date of 2001-12-17 and expiration date of 2026-12-17.

Our technology detection engine scanned swi-prolog.org and identified 2 distinct technologies across 2 categories. This analysis is performed by examining HTTP response headers, HTML source code patterns, JavaScript library fingerprints, CSS framework signatures, and DNS records. Hosting: GitHub Pages — provides the server infrastructure for swi-prolog.org. JavaScript Library: jQuery (version 3.6.0.) — provides utility functions and DOM manipulation for swi-prolog.org.

swi-prolog.org delivers its homepage in 9322ms (server response time), which is considered slow by industry standards. The total page weight is 10 KB, and we detected 93 resource requests loading assets from 8 third-party domains. A high number of third-party domains can significantly impact page load time due to additional DNS lookups and TLS handshakes required for each domain. The website uses Gzip compression for text-based assets, achieving an estimated 60.0% reduction in transfer size. This reduces bandwidth usage and improves page load times, especially for visitors on slower connections. Asset minification status: 1 out of 5 CSS files and 2 out of 4 JavaScript files are minified. Minifying the remaining 6 unminified file(s) could further reduce page weight by 10-30% for those assets. Minification is a best practice that reduces download sizes without affecting functionality. The site is served through a Content Delivery Network (CDN), which caches static assets at edge servers around the world. This means visitors from different geographic regions receive content from the nearest edge server, significantly reducing latency. CDN usage is particularly important for websites with a global audience, as it can reduce page load times by 40-60% for distant visitors. From an environmental perspective, each page view of swi-prolog.org produces approximately 0.0g of CO₂, earning a carbon rating of A. This places the website among the cleanest on the web, demonstrating efficient use of server resources and optimized content delivery. For reference, the average web page produces about 0.5g of CO₂ per page view. The page weight of 10 KB is the primary factor in this calculation. Core Web Vitals data from the Chrome User Experience Report (CrUX) is not available for swi-prolog.org. This typically means the site doesn't have enough real-world Chrome user traffic to generate statistically significant field data, or the domain is not included in the CrUX dataset. Core Web Vitals (LCP, INP, CLS) are important Google ranking factors that measure real user experience.

swi-prolog.org resolves to the IPv4 address 194.164.198.54 and also supports IPv6 (2a01:239:267:b900::1), demonstrating modern network infrastructure readiness. The domain has 1 A record(s) configured. The domain name system is managed by 3 name servers: ns0.transip.net, ns1.transip.nl, and ns2.transip.eu. Having 3 name servers provides good redundancy — if one fails, the others can continue serving DNS queries. The choice of name servers often indicates the DNS hosting provider or CDN service being used. Email for swi-prolog.org is handled by transip.email with 1 MX records configured: mx.transip.email. Multiple MX records provide failover redundancy — if the primary mail server is unavailable, email will be routed to the next available server. SPF (Sender Policy Framework) is configured, which specifies which mail servers are authorized to send email on behalf of this domain. This helps prevent email spoofing and improves email deliverability. DMARC (Domain-based Message Authentication, Reporting and Conformance) is configured with a none policy — a monitoring-only setting that doesn't enforce any action on unauthorized emails. DKIM was not detected. Without DKIM, recipients cannot cryptographically verify that emails claiming to be from this domain are authentic. DNSSEC is enabled for swi-prolog.org, providing an additional layer of security by cryptographically signing DNS records. This prevents DNS cache poisoning and man-in-the-middle attacks that could redirect visitors to malicious websites. The domain is registered through Key-Systems GmbH. It was first registered on 2001-12-17 and is set to expire on 2026-12-17, making it 24.6 years old. Our subdomain enumeration scan discovered 2 active subdomains for swi-prolog.org: dev.swi-prolog.org and www.swi-prolog.org. Active subdomains can reveal the organization's infrastructure, including development environments, API endpoints, and third-party service integrations.

The homepage of swi-prolog.org contains 208 words of visible text content. This is a relatively short page — adding more descriptive content could improve search engine visibility. The page is structured with 0 H2 headings, 0 H3 headings, 0 H4 headings. The page includes 16 images. All images have proper alt text attributes ✓, which is excellent for both accessibility (screen readers) and SEO (search engines can understand image content). The link structure consists of 47 internal links pointing to other pages on the same domain and 19 external links pointing to third-party websites. There are 4 external JavaScript files, 5 CSS stylesheets, and 0 iframes on the page. Notable missing features: XML Sitemap, robots.txt, and Schema.org structured data. Adding these could improve search engine discoverability and rich result eligibility. The website has social media presence across 1 platforms: Github (@SWI-Prolog). An active social media presence is a positive trust indicator and helps build brand awareness and customer engagement.

The title tag for swi-prolog.org is good at 10 characters: "SWI-Prolog". The length is acceptable, though it may be slightly truncated in some search result displays. No meta description is configured for swi-prolog.org. This is a critical SEO oversight — without a meta description, Google will auto-generate a snippet from page content, which may not accurately represent the page or entice users to click. Adding a unique, compelling meta description of 120-155 characters is strongly recommended. A favicon is configured. No Open Graph tags are configured. When someone shares a link to swi-prolog.org on social media, the platform will have to guess the title, description, and image — often producing unattractive or inaccurate previews. Adding OG tags is essential for social media marketing.