Mastodon gGmbH · Technology · Germany
Low risk. 3 critical or high findings in Security headers and GDPR outside view.
Mastodon gGmbH operates joinmastodon.org, a leading decentralized social media platform emphasizing user control, privacy, and open-source principles. The platform enables users to join or host independent servers, fostering a federated social network free from corporate control and advertising. The website reflects a mature, well-established non-profit organization with a clear mission and strong community support. Technically, the site employs modern web technologies such as Next.js and React, delivering fast performance and excellent mobile optimization. Security posture is solid with HTTPS enforcement and domain transfer protections, though DNSSEC is not enabled and some security policies are not publicly documented. Privacy compliance is good, with a comprehensive privacy policy but lacking explicit cookie consent mechanisms. Overall, the site is professional, trustworthy, and well-positioned in the decentralized social media market.
Scanned
NIS2 Art. 21(2)
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.
3 findings rated critical or high. Fix these first.
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.
Prevents clickjacking attacks
What to do: Add "X-Frame-Options: DENY" or "X-Frame-Options: SAMEORIGIN"
These are the privacy signals visitors and data protection authorities look for under GDPR.
GDPR requires clear information about cookie usage
What to do: Add a dedicated cookie policy explaining cookie usage and purposes
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
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Each check with its score, findings and the evidence it collected.
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
Not counted
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.
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
Leaked credentials and lookalike domains from OffSeq Breach. The counts are free; the detailed lists are paid add-ons.
Leaked records that mention joinmastodon.org, from OffSeq Breach.
4 subdomains affected
See the 10 newest leaked credentials
A one-off add-on to this report that lists the most recent identifier and password pairs OffSeq Breach holds for joinmastodon.org.
Select it in the checkout above.
Breach keeps ingesting new leaks, so these numbers can grow between scans.
Business context, site observations and technical notes gathered during the scan, and the standards behind each reference.
Automated reading of the public site. Ratings are indicative.
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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