Reion

A file-based API framework for Node.js and Bun. Define routes as files under an router directory, add middleware, and run with hot reload in development or a built server in production.

Prerequisites

• Node.js 18+ or Bun 1.0+
• TypeScript (recommended)

Quick start

This scaffolds a minimal project and starts the dev server (default: http://127.0.0.1:3000).

Add to an existing project

npm install reion
# or: bun add reion
# or: yarn add reion

Add a router/ directory under your app root (e.g. ./src/router when appDir is ./src, or ./router when appDir is ./). See Project structure below.

CLI

| Command | Description | |--------|-------------| | reion dev | Run the app with hot reload. | | reion build | Build for production (output in ./dist by default). | | reion start | Run the built app (no hot reload). |

Options (common)

• -p, --port <number> — Port (default: 3000).
• -H, --host <string> — Hostname (default: 127.0.0.1).
• --appDir <path> — App root (overrides config). Routes are loaded from {appDir}/router/**.
• --build-path <path> — Build output directory (for build / start).

Project structure

A minimal project:

my-api/
├── src/
│   └── router/
│       └── api/
│           └── hello/
│               └── route.ts   → GET /api/hello
├── reion.config.ts
├── package.json
└── tsconfig.json

• App directory (appDir in config, default ./src) — Routes live under router/, and middleware lives under router/**/middleware.ts. File paths under router/ map to URL paths.
• reion.config.ts — Optional: port, host, CORS, logging, dev options, plugins.

Your first route

Create src/router/route.ts (or router/route.ts if using appDir: "./"):

import type { Context } from "reion";

export async function GET(ctx: Context) {
  ctx.res.status(200);
  return { message: "Hello from Reion" };
}

This handles GET / and returns JSON.

Add src/router/api/hello/route.ts for GET /api/hello:

import type { Context } from "reion";

export async function GET(ctx: Context) {
  ctx.res.status(200);
  return { hello: "world" };
}

Export GET, POST, PUT, PATCH, DELETE, etc. from a route.ts file to handle those methods on the path that matches the file location.

Config

Example reion.config.ts:

import type { ReionConfig } from "reion";

const config: ReionConfig = {
  appDir: "./src", // option default ./src
  port: 3000,
  dev: {
    logPretty: true,
  },
};

export default config;

Environment variables

Reion loads environment variables automatically from the project root:

• .env
• .env.local
• .env.[mode] (for example: .env.development)
• .env.[mode].local (for example: .env.development.local)

Load order is:

1. .env
2. .env.local
3. .env.[mode]
4. .env.[mode].local

mode comes from NODE_ENV (development default in reion dev, production default in reion start).

Precedence rules:

• Existing environment variables (for example from shell/CI) are never overwritten.
• Files only fill keys that are not already present in process.env.

This works out of the box for reion dev and reion start, so you can read vars in reion.config.ts and route handlers without installing dotenv.

License

See the repository for license information.