FailClosed builds tools for IT and cybersecurity professionals. Free items are marked Free; anything sold separately is marked Buy and links out to where it’s actually purchased.
Claude Skills
Skill
ai-generalized-pentest-skills
Eight reusable Claude Code skills covering a full authorized penetration-testing engagement — enumeration, CVE fingerprinting, key-system triage, offensive tooling, system hardening, diagramming, report writing, and report anonymization.
Presented at BSides Cleveland 2026 — "Pentesting with Claude Code"
Skill
ai-generalized-blueteam-skills
Six reusable Claude Code skills for the defensive side — detection engineering, email-authentication posture audits, Active Directory hygiene audits, log triage and timeline reconstruction, incident-response report writing, and annual security-awareness training builds.
Free Custom GPTs
The GPTs below are free to use, but using any custom GPT requires your own ChatGPT subscription from OpenAI (a paid plan is generally required to access custom GPTs) — that subscription is not included with, or provided by, these GPTs. Purchasing, maintaining, and paying for your ChatGPT subscription is entirely your own responsibility; FailClosed does not sell, resell, or provide ChatGPT access of any kind.
Free
Source Code License Assistant
Helps developers select the best open-source licenses based on project type, intended use, and compatibility. It even scans existing repositories for compliance issues.
Free
SMTP Tutor
Provides a deep dive into SMTP fundamentals, aids in troubleshooting email delivery and configuration, and shares best practices for securing your SMTP servers.
Free
Shadow Paw
A master ninja cat hacker who delivers swift and stealthy answers to network security questions.
Free
DNS Security Analyzer
Detects potential DNS hijacking, misconfigurations, and privacy risks while guiding you through the implementation of DNSSEC and other protective measures.