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Security report for mastodon.social

Mastodon gGmbH · Technology · N/a

Low risk. 2 critical or high findings in GDPR outside view.

Security score

83/100

Risk levelLow

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

Mastodon.social is the original and one of the largest servers in the Mastodon federated social network, operated by the Mastodon gGmbH non-profit organization. It provides a decentralized social media platform that emphasizes user control, privacy, and an ad-free experience. The platform targets a broad audience interested in open-source and federated social networking. Technically, the site employs modern web technologies including Ruby on Rails and React, with a well-structured frontend and backend architecture. The site is performant, mobile-optimized, and accessible, with good SEO practices. Security-wise, the site enforces HTTPS, uses strong security headers, and avoids exposing sensitive data. However, it lacks some compliance features such as cookie consent and explicit terms of service. Overall, the domain is privacy protected but aligns with the legitimate non-profit Mastodon entity, indicating high trustworthiness.

Scanned

This is an earlier scan of mastodon.social. View the latest report

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

2 findings rated critical or high. Fix these first.

  1. 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 mastodon.social

This scan found 14 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.

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

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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
85
Security headers
80
Email security
85
DNS health
90
Network security
100
GDPR outside view
58
Average
83

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

Mastodon.social holds a strong market position as the flagship Mastodon server, serving a large active user base (268K monthly active users). Its non-profit business model focuses on community-driven development and open-source principles. The platform's competitive advantage lies in its decentralized nature, absence of ads, and strong community support. Revenue streams are likely limited to donations and sponsorships. The target customers are privacy-conscious social media users and open-source advocates. The ecosystem includes partnerships with other federated services and open-source contributors. Strategic observations include the importance of maintaining trust and transparency to sustain growth and community engagement.

Security posture

The security posture of Mastodon.social is strong, with enforced HTTPS, comprehensive security headers, and no visible vulnerabilities in the provided content. The site follows best practices such as script integrity checks and minimal data exposure. However, the absence of a published security policy, incident response contacts, and vulnerability disclosure mechanisms represents a compliance gap. The platform appears GDPR compliant with a comprehensive privacy policy but lacks cookie consent mechanisms. Incident response readiness and security culture indicators are not explicitly visible but can be inferred as mature given the platform's reputation. Overall, the security maturity is high but could be improved with formalized policies and disclosures.

Recommendations

  1. Implement a cookie consent banner to comply with privacy regulations and improve user transparency.
  2. Publish a clear terms of service page accessible from the main navigation.
  3. Add a security policy page detailing frameworks, controls, and incident response procedures.
  4. Provide a vulnerability disclosure policy or security.txt file to encourage responsible reporting.
  5. Include explicit contact information for security and privacy inquiries to enhance trust.
Site observations

Automated reading of the public site. Ratings are indicative.

Business

Company
Mastodon gGmbH
Description
The original server operated by the Mastodon gGmbH non-profit
Key services
Decentralized social networking, Federated microblogging, User profile directory
Content quality
good
Branding
consistent

Technology

Stack
Ruby on Rails, React, Webpack, JavaScript ES Modules, Service Workers, WebSockets
Frameworks
Ruby on Rails, React
Platforms
Fediverse, Mastodon
Performance
fast
Mobile
good
Accessibility
good
SEO
good

Security

Observed score
90/100
Good practices seen
  • HTTPS enforced
  • No exposed sensitive data in HTML
  • Use of integrity attributes on scripts and stylesheets
  • No visible vulnerable libraries

Analytics and tracking

Tracking level
minimal
Privacy practices
excellent

Advertising

Transparency
excellent

Site quality

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

Key observations

  1. Website is fully accessible with rich content and active user posts.
  2. No signs of WAF or blocking mechanisms.
  3. WHOIS data is privacy protected but consistent with a legitimate non-profit entity.
  4. No contact emails or phone numbers explicitly listed on the explored page.
  5. Privacy policy is present and comprehensive; cookie consent is missing.
  6. No terms of service page detected on this page.
  7. No security.txt or vulnerability disclosure found.
  8. Website uses modern web technologies and good security practices.
  9. No advertising or tracking scripts detected in the provided HTML.
  10. Content is safe and suitable for general audiences.
Technical notes

Notes

The website uses a modern tech stack with Ruby on Rails backend and React frontend, leveraging ES modules and Webpack for efficient asset management. The site is well-optimized for performance and mobile devices, with good accessibility features. The use of integrity attributes on scripts and stylesheets enhances security. No CMS is detected, indicating a custom-built platform. Hosting provider details are not explicit but the site uses a dedicated domain with strong SSL configuration. Technical risks are minimal, with no visible deprecated or vulnerable libraries. Opportunities exist to improve compliance-related technical implementations such as cookie consent and security policy automation.
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. 66/100 −18Medium21 findingsView report
  2. 84/100Low22 findingsView report
  3. 84/100Low18 findingsView report
  4. 84/100Low18 findingsView report
  5. 84/100Low18 findingsView report
  6. 84/100Low18 findingsView report
  7. 84/100Low18 findingsView report
  8. 84/100Low18 findingsView report
  9. 84/100Low18 findingsView report
  10. 84/100Low18 findingsView report
  11. 84/100Low18 findingsView report
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