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Security report for tandem.net

Tripod Technology GmbH · Technology · Germany

Medium risk. 4 critical or high findings in Security headers, GDPR outside view and 2 other checks.

Security score

70/100

Risk levelMedium

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

Tandem, operated by Tripod Technology GmbH, is a well-established language exchange platform founded in 2011. It connects millions of users worldwide to practice languages through chat, voice, and video, supported by in-app tools for correction and translation. The company targets language learners globally, offering a freemium app model with a strong community focus. The website is professionally designed, mobile-optimized, and provides a seamless user experience with clear navigation and rich content. Technically, the site leverages modern frameworks like Next.js and is hosted on AWS, ensuring fast performance and scalability. Security posture is strong with HTTPS, security headers, and domain transfer protections, though DNSSEC is not enabled. Privacy compliance is good, with a comprehensive privacy policy and cookie consent mechanisms in place. However, explicit security policies and incident response contacts are not published, representing an area for improvement. Overall, the domain registration and website content are consistent, indicating a legitimate and credible business presence.

Scanned

NIS2 and GDPR posture

GDPR outside view
73/ 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

4 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

  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

  3. 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.

    • High

      Weak Protocols Supported

      Server supports weak protocols: TLSv1.1

      What to do: Disable TLS 1.0, TLS 1.1, and all SSL versions

      • CWE-327
      • OWASP A04:2025
      • ASVS V12.1.1

  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 staging.tandem.net points to unregistered service tandem-website-staging-alb-1110160726.us-east-1.elb.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 tandem.net

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

€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
67
Security headers
45
Email security
75
DNS health
60
Network security
100
GDPR outside view
73
Average
70

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

Tandem holds a strong market position as a leading language exchange app, supported by media recognition and app store accolades. Its business model focuses on community-driven language learning with premium features. The company operates primarily in the technology and education sectors, targeting individual language learners worldwide. The absence of exposed contact emails or phone numbers on the site suggests a focus on digital engagement through app downloads and in-app support. The partnership ecosystem is not explicitly detailed on the site, but the presence of multiple country-specific language exchange pages indicates a broad international reach. Growth indicators include millions of users and continuous app updates. Strategic observations suggest opportunities to enhance trust by publishing security and incident response policies and expanding contact channels.

Security posture

The website demonstrates a mature security posture with enforced HTTPS, multiple security headers, and domain transfer restrictions. No vulnerabilities or exposed sensitive data were detected in the HTML content. The cookie consent banner aligns with GDPR requirements, and the privacy policy is comprehensive. However, the lack of a published security policy, incident response plan, or security.txt file limits transparency for security researchers and users. DNSSEC is not enabled, which could be a potential DNS security enhancement. The site uses third-party scripts like Google Tag Manager, which should be regularly audited to prevent supply chain risks. Overall, the security maturity is good but could be improved by formalizing security governance documentation and incident response contacts.

Recommendations

  1. Enable DNSSEC on the tandem.net domain to enhance DNS security and prevent spoofing.
  2. Publish a dedicated security policy and incident response plan on the website to improve transparency and trust.
  3. Add a security.txt file at the root domain to facilitate responsible vulnerability disclosure.
  4. Provide explicit contact information for the Data Protection Officer or privacy/security contacts.
  5. Regularly audit and update third-party scripts and tracking tools to mitigate supply chain vulnerabilities.
Site observations

Automated reading of the public site. Ratings are indicative.

Business

Company
Tripod Technology GmbH
Description
Tandem is a language learning app that connects millions of people worldwide to teach each other languages through conversation exchange.
Key services
Language exchange partner matching, Chat, voice, video communication, In-app correction and translation tools
Content quality
excellent
Branding
consistent

Technology

Stack
React, Next.js, AWS DNS, JavaScript, CSS
Frameworks
Next.js
Platforms
Web, iOS, Android
Performance
fast
Mobile
excellent
Accessibility
good
SEO
good

Security

Observed score
90/100
Good practices seen
  • HTTPS enforced
  • ClientTransferProhibited domain status
  • Cookie consent banner implemented
  • No exposed emails or phone numbers in HTML
  • Use of secure app deep links

Analytics and tracking

Services
Google Tag Manager
Tracking level
moderate
Privacy practices
good

Advertising

Transparency
basic

Site quality

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

Key observations

  1. Website uses HTTPS with strong security headers
  2. Cookie consent banner present and functional
  3. No direct company emails or phone numbers exposed on homepage
  4. WHOIS data shows domain is stable and registered to the operating company
  5. Website content is rich, multilingual, and professionally designed
  6. No signs of phishing, malware, or suspicious redirects
  7. Use of modern web technologies and frameworks
  8. No explicit security or incident response policies published
Technical notes

Notes

The website is built using modern web technologies including React and Next.js, hosted on AWS infrastructure, which supports scalability and performance. The site is mobile-optimized with responsive design and uses efficient image loading techniques. SEO is supported by comprehensive meta tags and Open Graph data. Accessibility features are present but could be further enhanced with ARIA roles and landmarks. The absence of a known CMS suggests a custom or proprietary content management approach. Performance is fast with preloading and preconnecting to critical resources. Technical risks are minimal but include the lack of DNSSEC and potential dependency on third-party scripts. Overall, the technical infrastructure is robust and well-implemented.
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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