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Security report for jsfiddle.net

JSFiddle · Technology · N/a

Medium risk. 7 critical or high findings in Security headers, GDPR outside view and 1 other check.

Security score

65/100

Risk levelMedium

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

JSFiddle.net is a mature and popular online code playground and IDE that allows developers to test and share JavaScript, CSS, HTML, and CoffeeScript code snippets. Founded in 2009, it serves a global developer audience with a freemium business model including PRO subscription options and recently introduced AI code completion features in beta. The platform leverages modern web technologies such as the Monaco Editor and integrates AI models from Mistral for enhanced developer productivity. Technically, the site is well-implemented with fast performance, mobile optimization, and consistent branding. Security posture is solid with HTTPS enabled and domain transfer protections, though it lacks DNSSEC and some security headers. Privacy compliance is weak due to missing privacy and cookie policies. Overall, the domain registration is consistent and trustworthy, supporting the legitimacy of the service.

Scanned

This is an earlier scan of jsfiddle.net. View the latest report

NIS2 and GDPR posture

GDPR outside view
35/ 100 · High
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

7 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 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 Privacy Policy found

      GDPR requires a clear and accessible privacy policy

      What to do: Add a comprehensive privacy policy page and link to it prominently

    • 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 jsfiddle.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.

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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
65
Security headers
50
Email security
60
DNS health
80
Network security
100
GDPR outside view
35
Average
65

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

Breach exposure

Leaked credentials and lookalike domains from OffSeq Breach. The counts are free; the detailed lists are paid add-ons.

Dark web exposure

Add-on

Leaked records that mention jsfiddle.net, from OffSeq Breach.

Total records
33,639
Employees
0
Customers
33,593
Third parties
46
Weak passwords
13%

7 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 jsfiddle.net.

Select it in the checkout above.

Breach keeps ingesting new leaks, so these numbers can grow between scans.

Technical appendix

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

Business context

Business profile

JSFiddle holds a strong market position as a widely used online code editor and playground, targeting developers and programmers worldwide. Its freemium model with PRO subscriptions and AI enhancements indicates a focus on monetization and innovation. The absence of explicit contact information and privacy policies suggests room for improvement in transparency and compliance. The platform's partnership with Mistral AI for code completion reflects strategic technology alliances. The company operates in the technology sector with a medium-sized footprint and a long operational history since 2009.

Security posture

The website demonstrates a good security baseline with HTTPS enforced and domain status set to clientTransferProhibited, reducing risk of unauthorized domain transfers. However, the lack of DNSSEC and missing security headers such as Content-Security-Policy and X-Frame-Options are notable gaps. No incident response or vulnerability disclosure information is provided, which could hinder timely security communications. Forms present do not expose sensitive data visibly, but absence of explicit security policies and contact channels for security incidents is a concern. Overall, the security posture is moderate but could be enhanced with better transparency and technical controls.

Recommendations

  1. Publish comprehensive privacy and cookie policies to improve compliance and user trust.
  2. Implement DNSSEC to strengthen DNS security and prevent spoofing.
  3. Add standard security headers like Content-Security-Policy, X-Frame-Options, and Strict-Transport-Security.
  4. Provide clear incident response and vulnerability disclosure contacts or pages.
  5. Enhance accessibility features to improve usability for all users.
Site observations

Automated reading of the public site. Ratings are indicative.

Business

Company
JSFiddle
Description
JSFiddle is an online IDE and playground for testing JavaScript, CSS, HTML, and CoffeeScript code snippets.
Key services
Online code editor, Code collaboration, Code sharing, AI code completion (beta)
Content quality
good
Branding
consistent

Technology

Stack
JavaScript, CSS, HTML, CoffeeScript, Monaco Editor, Mistral AI (Codestral)
Platforms
Web
Performance
fast
Mobile
good
Accessibility
basic
SEO
basic

Security

Observed score
75/100
Good practices seen
  • HTTPS enabled
  • clientTransferProhibited domain status

Analytics and tracking

Services
Custom analytics_jsf function
Tracking level
minimal
Privacy practices
poor

Advertising

Tracking pixels
analytics_jsf (custom analytics function)
Transparency
poor

Site quality

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

Key observations

  1. Website is a well-established online code playground for developers.
  2. No explicit privacy, cookie, or terms of service policies found in the provided HTML.
  3. Uses modern web technologies including Monaco Editor and AI code completion integration.
  4. No direct contact emails or phone numbers found in the HTML content.
  5. No security.txt or vulnerability disclosure information detected.
  6. No advertising networks or third-party trackers explicitly identified except custom analytics.
  7. Domain WHOIS data is consistent and domain is not privacy protected.
  8. No WAF or blocking mechanisms detected; content fully accessible.
Technical notes

Notes

JSFiddle uses a modern and robust technical stack centered on JavaScript, CSS, and HTML with the Monaco Editor for code editing capabilities. The integration of AI code completion via Mistral's Codestral model shows advanced technical maturity. Hosting and DNS are managed via Cloudflare, providing performance and security benefits. The site is well-optimized for performance and mobile devices, with good SEO basics in place. However, the absence of a CMS and limited accessibility features suggest areas for technical improvement. Overall, the infrastructure supports a reliable and scalable developer platform.
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. 67/100 −5Medium30 findingsView report
  2. 72/100Medium25 findingsView report
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