**subtls** is a minimal, proof‑of‑concept TypeScript TLS 1.3 client that implements a subset of the TLS 1.3 handshake and cipher suite using the Web Crypto API. It is intended for niche use‑cases—such as establishing TLS inside serverless V8 isolates or other TCP‑less environments where native TLS cannot be used—and for educational/experimental purposes, rather than production‑grade applications.