54 releases (24 stable)

2.0.0-alpha.0 Sep 22, 2021
1.7.7 Sep 10, 2021
1.7.6 Aug 13, 2021
1.7.5 Jun 2, 2021
0.1.0 Nov 30, 2017

#4 in FFI

Download history 5404/week @ 2021-07-03 3323/week @ 2021-07-10 4457/week @ 2021-07-17 3687/week @ 2021-07-24 5679/week @ 2021-07-31 5948/week @ 2021-08-07 7489/week @ 2021-08-14 7160/week @ 2021-08-21 7810/week @ 2021-08-28 4737/week @ 2021-09-04 5426/week @ 2021-09-11 7019/week @ 2021-09-18 6459/week @ 2021-09-25 7914/week @ 2021-10-02 38667/week @ 2021-10-09 46487/week @ 2021-10-16

23,972 downloads per month
Used in 2 crates

MIT license



Stake to support us chat

This project was initialized from xray

A minimal library for building compiled Node.js add-ons in Rust.


Prisma     swc     Parcel   next.js   nextjs.svg

Platform Support

Lint Linux N-API@3 Linux musl macOS/Windows/Linux x64 Linux-aarch64 Linux-armv7 macOS-Android Windows i686 Windows arm64 FreeBSD

node12 node14 node16
Windows x64
Windows x86
Windows arm64
macOS x64
macOS aarch64
Linux x64 gnu
Linux x64 musl
Linux aarch64 gnu
Linux aarch64 musl
Linux arm gnueabihf
Linux aarch64 android
FreeBSD x64

This library depends on Node-API and requires Node@10.0.0 or later.

We already have some packages written by napi-rs: node-rs

One nice feature is that this crate allows you to build add-ons purely with the Rust/JavaScript toolchain and without involving node-gyp.


You can start from package-template to play with napi-rs

Define JavaScript functions

extern crate napi;

// import the preludes
use napi::bindgen_prelude::*;

/// module registerion is done by the runtime, no need to explicitly do it now.
fn fibonacci(n: u32) -> u32 {
  match n {
    1 | 2 => 1,
    _ => fibonacci_native(n - 1) + fibonacci_native(n - 2),

/// use `Fn`, `FnMut` or `FnOnce` traits to defined JavaScript callbacks
/// the return type of callbacks can only be `Result`.
fn get_cwd<T: Fn(String) -> Result<()>>(callback: T) {

/// or, define the callback signature in where clause
fn test_callback<T>(callback: T)
where T: Fn(String) -> Result<()>

Checkout more examples in examples folder


This repository is a Cargo crate. Any napi-based add-on should contain Cargo.toml to make it a Cargo crate.

In your Cargo.toml you need to set the crate-type to "cdylib" so that cargo builds a C-style shared library that can be dynamically loaded by the Node executable. You'll also need to add this crate as a dependency.

name = "awesome"

crate-type = ["cdylib"]

napi = "2"
napi-derive = "2"

napi-build = "1"

And create build.rs in your own project:

// build.rs
extern crate napi_build;

fn main() {

So far, the napi build script has only been tested on macOS Linux Windows x64 MSVC and FreeBSD.

Install the @napi-rs/cli to help you build your Rust codes and copy Dynamic lib file to .node file in case you can require it in your program.

  "package": "awesome-package",
  "devDependencies": {
    "@napi-rs/cli": "^1.0.0"
  "napi": {
    "name": "jarvis" // <----------- Config the name of native addon, or the napi command will use the name of `Cargo.toml` for the binary file name.
  "scripts": {
    "build": "napi build --release",
    "build:debug": "napi build"

Then you can require your native binding:


The module_name would be your package name in your Cargo.toml.

xxx => ./xxx.node

xxx-yyy => ./xxx_yyy.node

You can also copy Dynamic lib file to an appointed location:

napi build [--release] ./dll
napi build [--release] ./artifacts

There are documents which contains more details about the @napi-rs/cli usage.


Because libraries that depend on this crate must be loaded into a Node executable in order to resolve symbols, all tests are written in JavaScript in the test_module subdirectory.

To run tests:

yarn build:test
yarn test

Related projects

Features table

Rust Type Node Type NAPI Version Minimal Node version
u32 Number 1 v8.0.0
i32/i64 Number 1 v8.0.0
f64 Number 1 v8.0.0
bool Boolean 1 v8.0.0
String/&'a str String 1 v8.0.0
Latin1String String 1 v8.0.0
UTF16String String 1 v8.0.0
Object Object 1 v8.0.0
Array Array 1 v8.0.0
Vec Array 1 v8.0.0
Buffer Buffer 1 v8.0.0
Null null 1 v8.0.0
Undefined/() undefined 1 v8.0.0
Result<()> Error 1 v8.0.0
T: Fn(...) -> Result function 1 v8.0.0
(NOT YET) global 1 v8.0.0
(NOT YET) Symbol 1 v8.0.0
(NOT YET) Promise 1 b8.5.0
(NOT YET) ArrayBuffer/TypedArray 1 v8.0.0
(NOT YET) threadsafe function 4 v10.6.0
(NOT YET) BigInt 6 v10.7.0


~42K SLoC