It uses its own DNS resolver (Hickory DNS), validates all resolved IPs against a blocklist (loopback, RFC 1918, link-local, cloud metadata, etc.), and pins the TCP connection to the validated IP so there's no TOCTOU gap to exploit.
Also supports domain allowlists/blocklists, rate limiting, body size limits, and timeouts.
Available as a Rust crate and npm package (native Node.js bindings via NAPI).
Built for tool-based agent architectures (MCP, LangChain, etc.) where you control what the agent can call. Not a replacement for container isolation but if your agent only talks to the outside world through HTTP, this locks it down.