@tsgonest/platform-bun

npm install @tsgonest/platform-bun

A NestJS HTTP adapter backed by Bun.serve(). Drop-in replacement for @nestjs/platform-express or @nestjs/platform-fastify.

Quick start

import { NestFactory } from '@nestjs/core';
import { BunAdapter } from '@tsgonest/platform-bun';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create(AppModule, new BunAdapter());
  await app.listen(3000);
}
bootstrap();

Run with Bun:

bun dist/main.js

Or use tsgonest's built-in Bun runtime support:

tsgonest dev --runtime bun

Bun runtime in dev mode

tsgonest's dev command supports Bun as a runtime. No adapter needed for this — it simply runs your compiled JS with bun instead of node.

Via CLI flag

tsgonest dev --runtime bun

Via config

// tsgonest.config.ts
import { defineConfig } from '@tsgonest/runtime';

export default defineConfig({
  runtime: 'bun',
});

CLI flag takes precedence over config. When using Bun, --enable-source-maps is automatically omitted (Bun enables it by default).

Performance

Benchmarked on macOS ARM64, NestJS 11, with tsgonest compile-time serialization in the loop:

vs Express (most NestJS users)

vs Fastify

Latency under load (500 connections)

Optimizations

The adapter applies several Elysia-inspired optimizations:

• No new URL() per request — URL pathname extracted via string slicing
• Lazy headers/query — only materialized when accessed by the handler
• Zero-Promise response path — Response built synchronously after handler completes (no deferred Promise allocation)
• Two-tier routing — static routes via O(1) Map lookup, param routes via pre-compiled regex
• Middleware bypass — when no middleware is registered, the chain is skipped entirely
• Plain object headers — passed directly to new Response() init (Bun optimizes this path)

API

BunAdapter

Extends NestJS's AbstractHttpAdapter. Compatible with NestJS 10 and 11.

import { BunAdapter } from '@tsgonest/platform-bun';

const app = await NestFactory.create(AppModule, new BunAdapter());

Supported NestJS features

• Route registration (@Get, @Post, @Put, @Delete, @Patch, @Options, @Head, @All)
• Route parameters (:id)
• Middleware (app.use())
• CORS (app.enableCors())
• Body parsing (JSON, text, form-urlencoded — Bun's native parser)
• Custom error handlers
• Custom 404 handlers
• TLS/HTTPS
• Guards, interceptors, pipes, exception filters (via NestJS core)

Not yet supported

• Static file serving (app.useStaticAssets()) — use Bun.file() or a reverse proxy
• View engines (app.setViewEngine()) — use a dedicated template engine
• WebSocket gateway — requires separate adapter

Requirements

• Bun >= 1.0 as the runtime
• NestJS >= 10.0
• @tsgonest/runtime for tsgonest serialization (optional — works without tsgonest too)