# Set up your Node.js server configuration for Web builds

> Information about how to set up your Node.js server to serve your Web build.

Create a Node.js server configuration file that lets your Node.js server work with your Unity Web build.

Node.js is an open-source runtime environment that lets you execute JavaScript code on the server side. In Unity, you can use a Node.js app to serve your Unity Web build.

For more information about Node.js and how to install and use it, refer to the [Node.js documentation](https://nodejs.org/en/learn/getting-started/introduction-to-nodejs).

## Set up your package.json file

To create a package.json file that's ready for use with Unity Web:

1. Create a file in a text editor or IDE.

2. Name the file `package.json`.

3. Save your file in your Node.js project directory.

4. Paste the following code into the file:

   ```lang-json
   {
     "name": "node_server_example",
     "version": "1.0.0",
     "description": "An example for serving a Unity Web build with Node.js",
     "main": "index.js",
     "dependencies": {
       "express": "^4.19.2"
     }
   }
   ```

Your `package.json` file is now ready for use. The code defines the `index.js` file as your server project's entry point, and defines the libraries your project will depend on.

## Set up your index.js file

To prepare your index.js file for use with Unity Web:

1. Create a file in a text editor or IDE.

2. Name the file `index.js`.

3. Save your file in your Node.js project directory.

4. Paste the following code into the file:

   ```lang-javascript
   #!/usr/bin/env node
   const path = require('path');
   const express = require('express');

   // Create express application
   const app = express();

   // Settings
   const hostname = 'localhost';
   const port = 8080;
   const enableCORS = true; 
   const enableWasmMultithreading = true;


   // Serve the current working directory 
   const unityBuildPath = __dirname; // Note: this makes the current working directory visible to all computers over the network.

   app.use((req, res, next) => {
       var path = req.url;

       // Provide COOP, COEP and CORP headers for SharedArrayBuffer
       // multithreading: https://web.dev/coop-coep/
       if (enableWasmMultithreading &&
           (
               path == '/' ||
               path.includes('.js') ||
               path.includes('.html') ||
               path.includes('.htm')
           )
       ) {
           res.set('Cross-Origin-Opener-Policy', 'same-origin');
           res.set('Cross-Origin-Embedder-Policy', 'require-corp');
           res.set('Cross-Origin-Resource-Policy', 'cross-origin');
       }

       // Set CORS headers
       if (enableCORS) {
           res.set('Access-Control-Allow-Origin', '*');
       }    

       // Set content encoding depending on compression
       if (path.endsWith('.br')) {
           res.set('Content-Encoding', 'br');
       } else if (path.endsWith('.gz')) {
           res.set('Content-Encoding', 'gzip');
       }

       // Explicitly set content type. Files can have wrong content type if build uses compression.
       if (path.includes('.wasm')) {
           res.set('Content-Type', 'application/wasm');
       } else if (path.includes('.js')) {
           res.set('Content-Type', 'application/javascript');
       } else if (path.includes('.json')) {
           res.set('Content-Type', 'application/json');
       } else if (
       path.includes('.data') ||
       path.includes('.bundle') ||
       path.endsWith('.unityweb')
       ) {
           res.set('Content-Type', 'application/octet-stream');
       }

       // Ignore cache-control: no-cache 
       // when if-modified-since or if-none-match is set
       // because Unity Loader will cache and revalidate manually
       if (req.headers['cache-control'] == 'no-cache' &&
       (
           req.headers['if-modified-since'] ||
           req.headers['if-none-match']
       )
       ) {       
           delete req.headers['cache-control'];
       }        

       next();
   });

   app.use('/', express.static(unityBuildPath, { immutable: true }));

   const server = app.listen(port, hostname, () => {
       console.log(`Web server serving directory ${unityBuildPath} at http://${hostname}:${port}`);
   });

   server.addListener('error', (error) => {
       console.error(error);
   });

   server.addListener('close', () => {
       console.log('Server stopped.');
       process.exit();
   });
   ```

5. If your build loads via CORS (for example, embedded on different website), then set the following line in your code to `true`, otherwise set it to `false`:

   ```lang-js
   const enableCORS = true; 
   ```

6. If you created your build with multithreading support, set the following line in your code to `true`, otherwise set it to `false`:

   ```lang-js
   const enableWasmMultithreading = true;
   ```

Your server configuration is now ready for use with Unity Web builds.

## Additional resources

* [Compressed builds and server configuration](/engine/6000.0/manual/platform-specific/webgl/building-distribution/deploying.md)
* [Server configuration code samples](/engine/6000.0/manual/platform-specific/webgl/building-distribution/server-configuration-code-samples.md)
* [Set up your IIS server configuration for Web builds](/engine/6000.0/manual/platform-specific/webgl/building-distribution/server-configuration-code-samples/web-server-config-iis.md)
* [Set up your Apache server configuration for Web builds](/engine/6000.0/manual/platform-specific/webgl/building-distribution/server-configuration-code-samples/web-server-config-apache.md)
* [Set up your Nginx server configuration for Web builds](/engine/6000.0/manual/platform-specific/webgl/building-distribution/server-configuration-code-samples/web-server-config-nginx.md)