circl.lu

We performed a comprehensive analysis of circl.lu on 2026-06-29. The website returned an HTTP 200 status code with a server response time of 3516ms. The page is served over HTTP/1.1 protocol with Gzip compression enabled, achieving approximately 60.0% size reduction. The total page weight is 18 KB. The website uses a secure HTTPS connection with a valid SSL certificate issued by DigiCert Inc (OV type). The connection is encrypted using TLS 1.2 with the ECDHE-RSA-AES256-GCM-SHA384 cipher suite and sha256WithRSAEncryption signature algorithm. The certificate covers 2 domain(s) (Subject Alternative Names) and expires on 2026-10-04, which is 97 days from now. The security headers analysis reveals a score of 70/100 (good). The following security headers are properly configured: Content-Security-Policy, Strict-Transport-Security (HSTS), X-Frame-Options, and X-Content-Type-Options. However, the site is missing 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 1 technologies across 1 categories powering circl.lu. The detected stack includes Font Awesome. Based on our comprehensive analysis of domain age, SSL configuration, email authentication, security headers, and blacklist status, circl.lu receives an overall trust score of 82/100, classified as "Very Likely Safe".

After conducting a thorough safety and legitimacy analysis, circl.lu receives a trust score of 82/100, which places it in the "Very 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 DigiCert Inc with 97 days until expiration, SPF (Sender Policy Framework) email authentication preventing email spoofing, DMARC email authentication with a none policy, and DNSSEC providing authenticated DNS responses. Areas of concern include: 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 circl.lu 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.

Our technology detection engine scanned circl.lu and identified 1 distinct technologies across 1 categories. This analysis is performed by examining HTTP response headers, HTML source code patterns, JavaScript library fingerprints, CSS framework signatures, and DNS records. Icon Set: Font Awesome — provides additional functionality for circl.lu.

circl.lu delivers its homepage in 3516ms (server response time), which is considered slow by industry standards. The total page weight is 18 KB, and we detected 113 resource requests loading assets from 6 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 2 CSS files and 0 out of 0 JavaScript files are minified. Minifying the remaining 1 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. From an environmental perspective, each page view of circl.lu produces approximately 0.01g 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 18 KB is the primary factor in this calculation. Core Web Vitals data from the Chrome User Experience Report (CrUX) is not available for circl.lu. 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.

circl.lu resolves to the IPv4 address 185.194.93.14 and also supports IPv6 (2a00:5980:93::14), demonstrating modern network infrastructure readiness. The domain has 1 A record(s) configured. The domain name system is managed by 4 name servers: ns-a.eurodns.com, ns-b.eurodns.org, ns-c.eurodns.eu, and ns-d.eurodns.biz. Having 4 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 circl.lu is handled by circl.lu with 1 MX records configured: cppy.circl.lu. 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 circl.lu, 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 homepage of circl.lu contains 1,277 words of visible text content. This is a substantial amount of content that provides good opportunities for search engine indexing. The page is structured with 0 H2 headings, 4 H3 headings, 0 H4 headings. The page includes 5 images. 1 images (20%) are missing alt text attributes, which is a significant concern for both accessibility and SEO. Screen readers rely on alt text to describe images to visually impaired users, and search engines use alt text to understand image content. Only 80% of images have proper alt text — we recommend adding descriptive alt attributes to all images. The link structure consists of 89 internal links pointing to other pages on the same domain and 14 external links pointing to third-party websites. There are 0 external JavaScript files, 2 CSS stylesheets, and 0 iframes on the page. The site implements the following web standards and features: XML Sitemap (helps search engines discover all pages), robots.txt (controls search engine crawling behavior), and RSS feed for content syndication. Notable missing features: Schema.org structured data. Adding these could improve search engine discoverability and rich result eligibility. We detected the following payment methods accepted on circl.lu: Visa and Discover. Offering multiple payment options including credit cards and digital wallets improves customer trust and can increase conversion rates. The website has social media presence across 2 platforms: Twitter (@circl_lu) and Github (@CIRCL). An active social media presence is a positive trust indicator and helps build brand awareness and customer engagement.

The title tag for circl.lu is too long at 78 characters: "CIRCL » CIRCL -- Computer Incident Response Center Luxembourg -- CSIRT -- CERT". At 78 characters, the title will likely be truncated in Google search results (recommended: 50-60 characters). Consider shortening it while keeping the most important keywords at the beginning. The meta description is 353 characters (slightly long): "The Computer Incident Response Center Luxembourg (CIRCL) is a government-driven initiative designed to gather, review, r...". Google typically displays up to 155-160 characters of the meta description in search results. A compelling meta description with a clear call-to-action can significantly improve click-through rates from search results. The page language is declared as en. No Open Graph tags are configured. When someone shares a link to circl.lu 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.