security-audit-skill

Free: MIT licensed with no license fee. Install through the Skills CLI (npx skills add, pointed at the repo with --skill security-audit) and run as many audits as you want. Security questions get a lighter guidance mode; the full six-phase workflow runs when you ask for a codebase audit or pen-test.

Self-hosted: Runs inside your own coding agent, so there's no service to operate. Requirements: an agent whose model supports tool use and parallel sub-agents, and Node.js for the zero-dependency findings and coverage-ledger validators. Confirming findings by running the target's code needs an OS-enforced sandbox (no external network, allowlisted environment, resource limits); without it the skill stays read-only and leaves leads as needs_validation. Output defaults to ~/security-audit-skill/<repo-name>/run-<N>.

Paid: No paid tier for the skill. Your spend is model tokens, and it scales with agent count: each coverage unit is roughly one hunter assignment and each surviving candidate one or two verifier assignments. You can set a budget as a maximum number of agent invocations. Multiple runs are additive, and Cloudflare reports a single run finds roughly half of what repeated runs find, so plan for more than one.