#deno #bindgen #bindings #macro

app deno_bindgen_cli

This tool aims to simplify glue code generation for Deno FFI libraries written in Rust

1 unstable release

0.1.0 Nov 12, 2023

#66 in FFI

MIT license

752 lines


This tool aims to simplify glue code generation for Deno FFI libraries written in Rust.


Install the command-line via cargo:

cargo install deno_bindgen_cli


use deno_bindgen::deno_bindgen;

// Export `add` function to JavaScript.
fn add(a: u32, b: u32) -> u32 {
    a + b

Use the exported functions directly in ESM with TypeScript typings

import { add } from "./bindings/mod.ts";

add(1, 2);


The tool is designed to make it very easy to write high performance FFI bindings. A lot of the things have been redesigned in 0.10 to prevent perf footguns.

TypeScript types are generated and supported OOTB.

All class handles support disposing memory via the Explicit Resource Management API (using).

pub struct Foo;

impl Foo {
  pub fn new() -> Self {

  pub fn bar(&self) {
    // ...
import { Foo } from "@ffi/example";

  using foo = new Foo();
  // foo is disposed here...

High performance. Codegen tries its best to take the fastest possible path for all bindings as-if they were written by hand to properly leverage the power of the Deno FFI JIT calls.

> make bench
cpu: Apple M1
runtime: deno 1.38.0 (aarch64-apple-darwin)

benchmark      time (avg)        iter/s             (min … max)       p75       p99      p995
--------------------------------------------------------------- -----------------------------
add             6.88 ns/iter 145,297,626.6    (6.78 ns … 13.33 ns)   6.81 ns   8.22 ns    9.4 ns
bytelen         8.05 ns/iter 124,278,976.3     (7.81 ns … 18.1 ns)   8.09 ns  10.39 ns  11.64 ns


By default, deno_bindgen generates bindings for local development. To publish a cross-platform binding, you can use the --lazy-init flag, this gives you full control on how you want to host pre-built shared libraries and pull them in at runtime.

deno_bindgen --release --lazy-init
import { add, load } from "./example/mod.ts";
import { cache } from "https://deno.land/x/cache/mod.ts";

// Download the shared library from a CDN
const file = await cache("https://example.com/example.so");

add(1, 2);


~70K SLoC