The hand-derived
JavaScript runtime.

cruft is a JavaScript runtime written from scratch in Rust — derived under Pin-Art discipline against ECMA-262 + WHATWG, conformance-measured against all of test262, and secure by capability-passing.

$ curl -fsSL https://cruft.sh/install | sh
Install cruft 4b88b8bc2 · or npm

Hand-derived runtime

A JavaScript runtime written from scratch in Rust — derived under Pin-Art discipline directly from ECMA-262 + WHATWG, not forked from an existing engine.

Conformance-first

Measured continuously against the full TC39 test262 corpus by the native cruft test262 sweep harness — 0 silent drops over the whole suite.

Node-compatible

Targets the Node.js package ecosystem: node:* modules plus canonical cruft:* surfaces, with npm install built in (cruft install).

Capability-passing security

No ambient authority — closed import graphs make whole classes of supply-chain attacks architecturally impossible, not merely audited.

93.1%
test262 runnable pass rate
49,628
tests passing of 53,289
0
silent drops · whole-suite sweep

Install

# the install one-liner (downloads the prebuilt binary, verifies sha256)
curl -fsSL https://cruft.sh/install | sh

# or via npm — the cruft runtime as a package
npm i -g @cruftless/cruft

# run a file
cruft index.js

Conformance is the spec, not the vibe.

Every build is swept against the full TC39 test262 corpus by the native cruft test262 sweep harness — one process per test, a total verdict classifier, zero silent drops. The number above is over the whole suite, against the true denominator. The Node binary is the differential oracle.