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Security report for similarweb.com

Similarweb Ltd. · Technology · N/a

Medium risk. 5 critical or high findings in SSL/TLS, Security headers and 2 other checks.

Security score

59/100

Risk levelMedium

0–100, higher is better. How it is calculated

Similarweb Ltd. operates a sophisticated AI-powered digital data intelligence platform that delivers real-time market intelligence, competitive insights, and consumer trend analysis to a broad audience of business professionals, marketers, investors, and researchers. Positioned as a leader in the digital analytics and market intelligence sector, Similarweb offers a comprehensive suite of services including web intelligence, sales intelligence, app intelligence, and data-as-a-service solutions. Their platform supports strategic decision-making and business growth through actionable digital insights. Technically, the website leverages a modern technology stack centered on React 17, integrated with advanced analytics tools such as Google Analytics (GA4) and Matomo, and employs robust privacy and consent management via Cookiebot. Hosting infrastructure appears to be secured and scalable, utilizing AWS services with Web Application Firewall (WAF) protections. The site demonstrates excellent performance, mobile optimization, and SEO practices, reflecting a mature digital presence. From a security perspective, Similarweb enforces HTTPS, employs security best practices including consent management and script integrity, and shows no signs of exposed sensitive data or vulnerabilities. However, explicit security headers like X-Frame-Options and X-Content-Type-Options were not confirmed and could be audited further. The absence of a public vulnerability disclosure policy is noted as an area for improvement. Overall, the website presents a low-risk profile with strong business credibility and technical maturity. The lack of WHOIS transparency due to privacy protection is typical for enterprises but slightly reduces trustworthiness. Strategic recommendations include enhancing security header implementation, establishing a public vulnerability disclosure channel, and maintaining rigorous third-party script audits to sustain security and compliance.

Scanned

NIS2 and GDPR posture

GDPR outside view
58/ 100 · Medium
Checks completed
7of 7

NIS2 Art. 21(2)

  1. (a) Risk analysis and security policies: Not visible from outside
  2. (b) Incident handling: One indicator
  3. (c) Business continuity, backups and crisis management: Not visible from outside
  4. (d) Supply chain security: Not visible from outside
  5. (e) Secure acquisition, development and maintenance, including vulnerability handling: Partly checked
  6. (f) Assessing the effectiveness of security measures: Not visible from outside
  7. (g) Cyber hygiene and security training: Not visible from outside
  8. (h) Cryptography and encryption: Partly checked
  9. (i) HR security, access control and asset management: One indicator
  10. (j) Multi-factor authentication and secured communications: Not visible from outside

This scan rated NIS2 with an earlier keyword method that is no longer shown; rescan for the per-article view. Risk management, continuity, supply chain, training, MFA, management oversight (Art. 20) and incident reporting (Art. 23) need internal evidence, and Guard cannot tell whether NIS2 applies to this organisation.

GDPR is indicative only, based on publicly visible signals: Articles 7, 12, 13 and 32 of Regulation (EU) 2016/679 and Article 5(3) of the ePrivacy Directive. Not a certification or legal assessment.

Priority findings

5 findings rated critical or high. Fix these first.

  1. SSL/TLS

    TLS encrypts the connection and proves the site is really yours. Weak or expiring certificates trigger browser warnings and put traffic at risk.

    • Critical

      Unable to retrieve SSL certificate

      Could not establish secure connection to retrieve certificate information

      What to do: Check if the server is accessible and SSL/TLS is properly configured

  2. Security headers

    Security headers are instructions your web server sends to every visitor’s browser. Missing ones leave visitors more exposed to attacks such as clickjacking and injected scripts.

    • High

      Missing X-Frame-Options header

      Prevents clickjacking attacks

      What to do: Add "X-Frame-Options: DENY" or "X-Frame-Options: SAMEORIGIN"

  3. GDPR outside view

    These are the privacy signals visitors and data protection authorities look for under GDPR.

    • High

      No Cookie Policy found

      GDPR requires clear information about cookie usage

      What to do: Add a dedicated cookie policy explaining cookie usage and purposes

    • High

      No Cookie Consent Banner found

      GDPR requires explicit consent for non-essential cookies

      What to do: Implement a cookie consent banner that appears on first visit

  4. DNS health

    DNS sends visitors and email to the right servers. Misconfigured records can cause outages or let someone redirect your traffic.

    • High

      Potential Subdomain Takeover

      Subdomain ftp.similarweb.com points to unregistered service s-d3cfc6eb1d9e46fe8.server.transfer.us-east-1.amazonaws.com

      What to do: Remove or fix CNAME record to prevent subdomain takeover

      • WSTG-CONF-10
      • NIS2 21(2)(i)
      • IR 2024/2690 12.4: Implementing Regulation (EU) 2024/2690, Annex point 12.4: Asset inventory
      • NIST CM-8: NIST SP 800-53 Rev. 5 CM-8: System Component Inventory

Need hands-on remediation? Email guard@offseq.com

Keep watching similarweb.com

This scan found 17 issues across 6 checks. Monitoring re-runs those checks daily, emails you when something material changes and records each fix, so you can show progress.

Daily monitoring

Recommended

€25per month

  • TLS certificates and expiry
  • DNS records
  • SPF, DKIM and DMARC
  • Security headers
  • GDPR and NIS2 posture
  • Exposed services
  • Third-party trackers
  • Security score drift

Email alerts on material changes and an exportable JSON history of every change.

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Full report

€39.90one-time

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Results by check

Each check with its score, findings and the evidence it collected.

How this score is calculated

The security score runs 0–100, higher is better. It is the plain average of the security checks that completed in this scan, each counted equally. A check that could not run is left out: it counts neither as a pass nor as a fail.

Counted in this score

SSL/TLS
0
Security headers
45
Email security
85
DNS health
65
Network security
100
GDPR outside view
58
Average
59

Not counted

  • NIS2 outside view: Re-weights evidence from the TLS, email, DNS, network and hygiene checks, so counting it would count that evidence twice. Shown on its own.
  • OffSeq Observations: An AI reading of the site, useful context but not reproducible evidence. Shown on its own.

Findings that cap the score at 49

Each of these is serious on its own, so while any is present the site cannot rate better than high risk, however good the other checks are.

  • The certificate is not trusted by browsers
  • The website is not served over HTTPS
  • A database, remote desktop, file-sharing or Telnet service is reachable from the internet
  • The page loads a script from a compromised source
  • The domain registration has expired
  • SPF authorises every server to send mail as the domain

Partial scans

When the site blocks Guard or most checks cannot run, the score covers only the checks that ran (usually DNS and email), is capped at 75 and is shown as partial, without a risk level.

Risk levels

  • Critical0–25
  • High26–49
  • Medium50–75
  • Low76–100

Technical appendix

Business context, site observations and technical notes gathered during the scan, and the standards behind each reference.

Business context

Business profile

Similarweb holds a strong market position as a leading provider of digital market intelligence and analytics solutions. Its SaaS business model targets enterprise clients seeking competitive insights and consumer behavior data to optimize marketing, sales, and investment decisions. The company’s ecosystem includes integrations with major platforms and a broad partner network evidenced by verified social media presence and industry recognition. The platform’s comprehensive service offerings and data-driven approach support diverse customer segments, including agencies, investors, and digital marketers. Growth indicators include continuous product innovation, AI integration, and expansion into app intelligence. The company maintains a consistent brand image and high-quality content, reinforcing its credibility and market leadership.

Security posture

The security posture of Similarweb’s website is robust, featuring HTTPS encryption, use of AWS WAF, and compliance with GDPR through cookie consent mechanisms. The site avoids exposing sensitive information and uses reputable analytics and tracking services with user consent. While core security headers are likely implemented, explicit confirmation is recommended. No vulnerabilities or suspicious scripts were detected in the provided content. The absence of a dedicated security policy or incident response contact is a gap that could be addressed to enhance transparency and readiness. Overall, the security maturity aligns with enterprise standards, supporting trust and data protection obligations.

Recommendations

  1. Conduct a security header audit to ensure all recommended headers (X-Frame-Options, X-Content-Type-Options, Content-Security-Policy) are properly configured.
  2. Establish and publish a formal vulnerability disclosure policy and security contact information to improve transparency and incident response.
  3. Regularly review and update third-party scripts and dependencies to mitigate risks from vulnerable libraries.
  4. Enhance privacy compliance by providing clear data retention policies and user data management options.
  5. Maintain continuous monitoring of WAF and security infrastructure to promptly detect and mitigate emerging threats.
Site observations

Automated reading of the public site. Ratings are indicative.

Business

Company
Similarweb Ltd.
Description
Similarweb is an AI-powered digital data company providing real-time market intelligence, competitive insights, and consumer trends to accelerate business growth.
Key services
real-time market intelligence, competitive insights, consumer trends analysis, digital marketing intelligence, sales intelligence, app intelligence, data as a service
Content quality
excellent
Branding
consistent

Technology

Stack
React 17.0.2, Google Tag Manager, Matomo Analytics, Cookiebot, FingerprintJS2, AWS WAF, Google Identity Services, Google Fonts, JSDelivr CDN
Frameworks
React
Platforms
Web
Performance
fast
Mobile
excellent
Accessibility
good
SEO
excellent

Security

Observed score
90/100
Good practices seen
  • HTTPS enforced
  • Cookie consent with region-based GDPR compliance
  • Use of AWS WAF for protection
  • No exposed sensitive data in HTML
  • Use of modern JS libraries with integrity

Analytics and tracking

Services
Google Analytics (GA4), Matomo
Tracking level
moderate
Privacy practices
good

Advertising

Ad networks
Bing Ads, Google Ads
Tracking pixels
Matomo, Cookiebot
Marketing tools
Cookiebot, FingerprintJS2
Transparency
good

Site quality

Design
excellent
User experience
excellent
Content relevance
excellent
Navigation
excellent
Professionalism
excellent
Trustworthiness
high

Key observations

  1. Website is fully accessible with no blocking or WAF challenge
  2. Content is rich, professional, and business-oriented
  3. Strong use of modern web technologies and analytics
  4. Good privacy and cookie compliance with consent mechanisms
  5. WHOIS data is missing or privacy-protected, common for large enterprises
  6. No security vulnerabilities or exposed sensitive data detected
  7. Multiple verified social media and trust signals present
Technical notes

Notes

The website is built on a modern React framework with asynchronous loading of scripts and optimized resource preloading, contributing to fast performance and excellent mobile responsiveness. Integration with Google Tag Manager, Matomo, and Cookiebot indicates a mature approach to analytics and privacy compliance. Hosting on AWS with WAF protection suggests scalable and secure infrastructure. The use of CDN services like JSDelivr and Google Fonts further enhances load times and reliability. No CMS was explicitly detected, implying a custom or proprietary platform. Overall, the technical implementation supports a high-quality user experience and robust operational stability.
Standards and sources

Reference chips under each finding point to the standard, regulation or specification the finding relates to. They are taken from the official datasets below and mapped conservatively: a finding with no defensible link shows none. NIS2 and GDPR references mark where a finding is relevant evidence, not a compliance verdict. Implementing Regulation (EU) 2024/2690 binds digital infrastructure and digital service providers; for other entities it is the most detailed public reading of the Article 21 measures. WCAG, EN 301 549, European Accessibility Act and Web Accessibility Directive references name the requirement an automated accessibility rule relates to; they are not a conformance verdict.

Retrieved 2026-10-25

Earlier scans of this domain

  1. 64/100Medium24 findingsView report
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