ZNTC

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Zig Native Transpiler & Compiler — a transpiler and bundler for JavaScript / TypeScript / Flow, written in Zig and shipped as a native NAPI addon.

ZNTC is a single-pass toolchain targeting the production quality of SWC / oxc / esbuild. Transpile and bundle share the same pipeline, and 1st-party transforms like styled-components / emotion / Reanimated worklets / Flow are built into the core — no Babel required.

• 📦 Single dependency — @zntc/core covers transpile + bundle + dev server (ships the zntc CLI)
• ⚡ Native speed — SIMD lexer, arena + mimalloc, index-based 24B fixed-size AST, producer-consumer pipeline
• 🔌 Plugin compatible — Rollup / Vite hooks (resolveId / load / transform) + esbuild-compatible CLI / options
• 📱 React Native first-class — Metro-compatible bundling, Flow, Reanimated worklets, Hermes target, dev server
• 🌐 Runs anywhere — Node 24+, Bun 1.3+, browser WASM (transpile-only and full bundler builds)

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Installation

# Node / Bun
bun add -D @zntc/core
# npm i -D @zntc/core
# pnpm add -D @zntc/core

Scenario	Additional package
transpile / bundle (library mode)	@zntc/core only
dev / preview / build (postcss · sass · CSS Modules · HMR overlay)	+ @zntc/web
Vite users — replace just the esbuild transform with ZNTC	@zntc/vite-plugin
React Native (init / preset / dev server)	+ @zntc/react-native
Browser playground / Workers	@zntc/wasm

Status: pre-release. Prebuilt NAPI binaries are provided for macOS / Linux / Windows × x64 / arm64. See docs/PUBLISH.md for the full build matrix.

Quick start

CLI

# Transpile a single file (.ts → .js, sourcemap included)
npx zntc src/index.ts --outdir dist

# Bundle (esbuild-compatible options)
npx zntc src/index.ts --bundle --outdir dist --format=esm --target=es2022

# Dev server + HMR + Fast Refresh
npx zntc --serve --bundle src/main.tsx --port 5173
# Or with the `dev` subcommand (root-based):
# npx zntc dev --port 5173

# React Native (Metro-compatible)
npx zntc --bundle index.js --platform=react-native --rn-platform=ios -o bundle.js

Run zntc --help for the full list of options.

@zntc/core JS / NAPI API

import { transpile, build } from "@zntc/core";

// Single-file transpile — the NAPI binding is loaded lazily on first use
const { code, map } = transpile(source, {
  filename: "input.ts",
  jsx: "automatic",
  target: "es2022",
  sourcemap: true,
});

// Bundle (esbuild / Vite / Rollup-compatible plugin hooks)
const result = await build({
  entryPoints: ["src/index.ts"],
  bundle: true,
  format: "esm",
  platform: "browser",
  target: ["chrome100", "safari16"],
  define: { "process.env.NODE_ENV": '"production"' },
  plugins: [
    {
      name: "my-plugin",
      setup(build) {
        build.onResolve({ filter: /^virtual:/ }, (args) => ({ path: args.path, namespace: "virtual" }));
        build.onLoad({ filter: /.*/, namespace: "virtual" }, () => ({ contents: "export const x = 1" }));
      },
    },
  ],
});

Vite integration

// vite.config.ts
import { defineConfig } from "vite";
import zntc from "@zntc/vite-plugin";

export default defineConfig({
  plugins: [zntc()],
});

Vite's esbuild transform step is swapped out for ZNTC, so TS / JSX / Flow and 1st-party transforms all flow through a single pass.

Attaching to a React Native CLI project

npx @zntc/init

This rewrites the start / bundle:* scripts of an existing RN CLI app to use ZNTC (Metro fallback is preserved). See the React Native guide and the zntc.config.ts example for details.

Features

1st-party transforms — no Babel

Transforms that require separate Babel plugins in other bundlers are built into the ZNTC core.

// zntc.config.ts
import { defineConfig } from "@zntc/core";

export default defineConfig({
  platform: "react-native",      // auto-enables flow / worklets / RN preset
  jsxImportSource: "@emotion/react",
  compiler: {
    styledComponents: true,      // covers babel-plugin-styled-components
    emotion: { autoLabel: "dev-only" },  // covers @emotion/babel-plugin
  },
});

Babel plugin	ZNTC option
babel-plugin-styled-components	compiler.styledComponents
@emotion/babel-plugin	compiler.emotion
react-native-worklets/plugin	workletTransform (automatic on RN)
@babel/preset-flow	flow: true (automatic on RN)
@babel/preset-env	target: "es2020" / target: "hermes0.70"

Details: native transforms guide.

Plugin / options compatibility

• Rollup / Vite-style hooks: resolveId, load, transform (supports filter functions, RegExp, and string)
• esbuild-compatible option surface: entryPoints, bundle, format, target, define, loader, external, metafile
• Vite alias compatible: both Record<string, string> and { find, replacement } array forms
• zntc.config.{ts,js,json} + tsconfig + .env + CLI flag with documented merge precedence (docs/CONFIG.md)

Performance

Metric	Result
Test262 TC39 conformance	50,504 / 50,504 pass (100%, 0 fail)
144-package npm smoke (build + execute)	average 0.82x bundle size vs esbuild
Synthetic bench (parse + emit)	ZNTC 7ms · Bun 10ms · esbuild 13ms · rolldown 62ms
RN core (react-native 0.74)	410 @flow files pass regression
HMR warm rebuild	< 100ms (PR #1747)

Full data: docs/ROADMAP.md · docs/TESTING.md · benchmark site.

Documentation

📚 Official docs: https://ohah.github.io/zntc

Key guides:

• Introduction · Installation · Quick start
• Config file · Native transforms (without Babel)
• Bundling overview · Tree shaking · Bundler deep dive
• React Native · Flow support · Migrating from Babel
• Plugins · Plugin recipes · Rspack / Webpack integration
• Tooling comparison · Migrating from other tools
• CLI reference · NAPI / JS API · Transpile options

Contributor docs (in-tree):

• docs/ARCHITECTURE.md · docs/BUNDLER.md · docs/HMR.md · docs/PLUGINS.md
• docs/ROADMAP.md · docs/TESTING.md · docs/DECISIONS.md · docs/INVARIANTS.md
• docs/FLOW.md · docs/DEBUG.md · docs/AST_PLUGINS.md · docs/BACKLOG.md

Packages

Package	Role
@zntc/core	NAPI .node binding + Node / Bun CLI (zntc) + transpile / bundle / lightningcss
@zntc/web	dev server + HMR overlay + postcss / sass pipeline + dev controller
@zntc/vite-plugin	Replace Vite's esbuild transform with ZNTC (only depends on @zntc/core)
@zntc/rspack-loader	TS / JSX / Flow loader for Rspack / Webpack (drop-in replacement for swc-loader / esbuild-loader)
@zntc/react-native	RN preset + Metro-compatible dev server + Reanimated worklets / Flow / Hermes
@zntc/init	npx @zntc/init — scaffold new projects or overlay an existing RN CLI app
@zntc/wasm	WASM build (browser playground / Deno / Workers)
@zntc/server	private — protocol / WS frame / watcher / HMR channel (inlined into @zntc/web dist; users do not install directly)

Status

Phase 1–6 largely complete — lexer / parser / semantic / transformer / codegen / bundler / dev server / HMR.

• Test262: 50,504 / 50,504 (100%), 0 fail
• npm package smoke: 144 / 144 passing (compared against esbuild / rolldown / rspack)
• RN core (react-native 0.74) 410 @flow files pass regression

Open issues and backlog: docs/ROADMAP.md · docs/BACKLOG.md · GitHub Issues.

Contributing

The core of ZNTC is written in Zig. You need Zig 0.15.2 to build from source (mise is recommended).

git clone https://github.com/ohah/zntc.git
cd zntc
mise install

# Build
zig build                          # zntc CLI + lib (Debug)
zig build -Doptimize=ReleaseFast   # for performance measurement
zig build run -- src/index.ts      # invoke the CLI directly

# Test
zig build test                     # Zig unit / integration tests
zig build test262-run              # run the 50,504 Test262 cases
zig build napi                     # NAPI .node for @zntc/core
zig build wasm                     # transpile-only WASM
zig build wasm-bundler             # bundler-inclusive WASM (wasm32-wasi + threads)
zig build schema                   # auto-generate the BuildOptions JSON schema

JS-side tests:

cd tests/integration && bun test       # CLI / NAPI integration
cd tests/e2e && bun test               # Playwright E2E
cd tests/benchmark && bun run smoke.ts # build + execute 144 packages vs esbuild / rolldown / rspack

Workflow — see CLAUDE.md: feature branch → PR → merge. Direct pushes to main are not allowed. PR titles use the feat(lexer): add numeric literal tokenization style; PR descriptions are written in Korean.

References

• Bun JS Parser (Zig, MIT) — parser / lexer / SIMD
• oxc (Rust, MIT) — transformer / reference flags
• SWC (Rust, Apache-2.0) — downlevel reference
• esbuild (Go, MIT) — bundler architecture / compatibility surface
• Rolldown (Rust, MIT) — Rollup-compatible / Vite integration
• Hermes (C++, MIT) — embedded Flow parser + RN runtime
• Metro (JS, MIT) — React Native bundler compatibility
• TypeScript (TS, Apache-2.0) — downlevel / decorator cases
• Test262 — TC39 conformance, 50,504 cases

License

MIT