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Security report for sheetjs.com

SheetJS · Technology · N/a

Medium risk. 6 critical or high findings in Security headers, GDPR outside view and 1 other check.

Security score

66/100

Risk levelMedium

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

SheetJS is a technology company specializing in tools for reading, editing, and exporting Excel spreadsheets. Their offerings include a community edition that is open source and a professional edition with enhanced features and priority support. The company is well-established with a domain age since 2013 and is trusted by major technology companies such as Microsoft, Google, Amazon, and Facebook, as well as US government websites. The website is professionally designed, mobile optimized, and uses modern web technologies including React and Gatsby, hosted on Cloudflare infrastructure. Analytics are implemented via Google Analytics and Cloudflare Pages Analytics. Security posture is good with HTTPS enforced and domain transfer protections, but lacks DNSSEC and security headers. Privacy compliance is partial with a privacy policy present but no cookie consent mechanism or GDPR explicit indicators. Contact information and security policies are not prominently published. Overall, the website is credible, technically sound, and business-focused with room for improvement in security and privacy transparency.

Scanned

NIS2 and GDPR posture

GDPR outside view
53/ 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

6 findings rated critical or high. Fix these first.

  1. 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 Strict-Transport-Security header

      Forces HTTPS connections

      What to do: Add "Strict-Transport-Security: max-age=31536000; includeSubDomains; preload"

      • CWE-319
      • OWASP A04:2025
      • ASVS V3.4.1
    • High

      Missing X-Frame-Options header

      Prevents clickjacking attacks

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

    • High

      Missing Content-Security-Policy header

      Controls resources the browser is allowed to load

      What to do: Implement a Content-Security-Policy appropriate for your application

      • ASVS V3.4.3
      • OWASP Secure Headers: OWASP Secure Headers Project recommends Content-Security-Policy: default-src 'self'; form-action 'self'; base-uri 'self'; object-src 'none';…

  2. 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

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

Keep watching sheetjs.com

This scan found 22 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

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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
75
Security headers
30
Email security
70
DNS health
70
Network security
100
GDPR outside view
53
Average
66

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

SheetJS operates in the technology sector providing spreadsheet manipulation tools primarily targeting developers and enterprises requiring robust data import/export and editing capabilities. Their business model combines open source community offerings with a paid professional edition, enabling revenue through licensing and support. The company has strong market positioning evidenced by adoption in leading tech firms and government agencies. The website content and branding are consistent and professional, supporting a medium-sized enterprise profile. The lack of explicit contact details and security policies suggests a focus on product and developer engagement rather than direct consumer sales or support. The partnership ecosystem is implied through usage by major companies but no direct partner domains are listed.

Security posture

The website demonstrates a moderate to good security posture with HTTPS enforced and domain transfer lock enabled. However, DNSSEC is not enabled, and no security headers were detected in the provided data, which are important for mitigating common web attacks. There is no publicly available security policy or incident response contact information, which limits transparency and readiness perception. The absence of a cookie consent mechanism also indicates partial GDPR compliance. No vulnerabilities or exposed sensitive data were detected in the analysis. Overall, the security maturity is adequate but could be improved by implementing recommended headers, DNSSEC, and publishing security policies.

Recommendations

  1. Enable DNSSEC on the domain to enhance DNS security.
  2. Implement standard security headers such as Content-Security-Policy, X-Frame-Options, and Strict-Transport-Security.
  3. Publish a clear security policy and incident response contact information on the website.
  4. Add a cookie consent banner/mechanism to comply with GDPR and other privacy regulations.
  5. Consider publishing a vulnerability disclosure policy and security.txt file to improve transparency and trust.
Site observations

Automated reading of the public site. Ratings are indicative.

Business

Company
SheetJS
Description
SheetJS provides tools for reading, editing, and exporting Excel spreadsheets, supporting web browsers and servers. It is trusted by Microsoft Office 365 and powers services at Google, Amazon, Facebook, and US Government websites.
Key services
Spreadsheet reading and editing, Spreadsheet exporting, Professional edition with advanced features and support
Content quality
good
Branding
consistent

Technology

Stack
JavaScript, React (Gatsby framework), Cloudflare hosting, Google Analytics
Frameworks
Gatsby
Platforms
Web browsers, Server environments
Performance
fast
Mobile
good
Accessibility
basic
SEO
good

Security

Observed score
75/100
Good practices seen
  • HTTPS enforced
  • Domain status clientTransferProhibited

Analytics and tracking

Services
Google Analytics, Cloudflare Pages Analytics
Tracking level
moderate
Privacy practices
basic

Advertising

Tracking pixels
Cloudflare Pages Analytics
Transparency
basic

Site quality

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

Key observations

  1. Website is fully accessible with no blocking or WAF challenges.
  2. Content is focused on spreadsheet software tools with clear business positioning.
  3. No direct contact emails or phone numbers found on the homepage or header.
  4. Privacy policy is present but cookie consent mechanism is missing.
  5. No visible forms collecting user data on the homepage.
  6. Use of modern web technologies and frameworks (Gatsby, React).
  7. Google Analytics and Cloudflare analytics scripts are present.
  8. No explicit security policies or incident response contacts published.
  9. No terms of service page detected from homepage links.
  10. No security headers detected in provided data; DNSSEC not enabled.
Technical notes

Notes

The website is built using modern JavaScript frameworks, specifically Gatsby and React, which support fast performance and good SEO. Hosting is provided by Cloudflare, ensuring reliable delivery and security features. Google Tag Manager and Google Analytics are used for traffic and user behavior analysis. The site is mobile optimized and accessible at a basic level. No CMS was detected, indicating a custom or static site generation approach. The technical implementation is solid with no broken elements or errors observed. However, the lack of security headers and DNSSEC represents technical debt in security hardening. Overall, the infrastructure supports a professional and scalable web presence.
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

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