Version: 2022.1
Build and distribute a WebGL application
Reduce load times with AssetBundles

Build your WebGL application

To create a build for WebGL, go to File > Build Settings from Unity’s main menu. In the Platform list, select WebGL and then click Switch Platform.

When you have configured the Build Settings, choose one the following options:

  • Build: Builds your application into a Player.
  • Build and Run: Builds your application in a Player, and opens that Player on your target platform.
Build Settings Window
Build Settings Window

The Unity build system for WebGLA JavaScript API that renders 2D and 3D graphics in a web browser. The Unity WebGL build option allows Unity to publish content as JavaScript programs which use HTML5 technologies and the WebGL rendering API to run Unity content in a web browser. More info
See in Glossary
supports the following settings:

Setting Function
Texture CompressionA method of storing data that reduces the amount of storage space it requires. See Texture Compression, Animation Compression, Audio Compression, Build Compression.
See in Glossary
The texture compression3D Graphics hardware requires Textures to be compressed in specialized formats which are optimized for fast Texture sampling. More info
See in Glossary
format to use for the build. The options are:
Use Player Settings This is the default selection. It uses the texture compression format you set in the Player settingsSettings that let you set various player-specific options for the final game built by Unity. More info
See in Glossary
window.
ETC2 Uses ETC2 format, which is widely supported on mobile devices.
ASTC Uses ASTC format, which is widely supported on mobile devices.
DXT Uses DXT format, which is widely supported on desktop devices.
Development BuildA development build includes debug symbols and enables the Profiler. More info
See in Glossary
Enable this setting to include scripting debug symbols and the Profiler in your build. When you enable this, Unity sets the DEVELOPMENT_BUILD scripting define. You should use this setting only when you want to test your application. The development builds don’t minify content, which means the development builds are large to distribute.
Code Optimization Select the optimization mode to use for compiling the WebGL code.
Speed This is the default setting. Select this to generate WebGL code that’s optimized for runtime performance.
Size Select this to generate WebGL code that’s optimized for build size. This is useful for reducing WebGL games to the smallest downloadable size, and for large projects if a mobile browser (Android or iOS) refuses to load the default optimize-for-speed WebAssembly builds as too large for mobile devices to consume.
Autoconnect Profiler Typically, when enabled, this setting allows you to automatically connect the Unity Profiler to your build. However for WebGL, as you can’t connect the ProfilerA window that helps you to optimize your game. It shows how much time is spent in the various areas of your game. For example, it can report the percentage of time spent rendering, animating, or in your game logic. More info
See in Glossary
to a running build, use this option to connect the content to the Editor instead. This is because the Profiler connection is handled using WebSockets on WebGL, but a web browser only allows outgoing connections from the content. For this setting to be available, you should enable the Development Build option.
Deep Profiling Enable this setting to activate Deep Profiling in the Profiler. This makes the Profiler instrument every function call in your application and returns more detailed profiling data. When you enable Deep Profiling Support, it might slow down script execution. This option is only available if you enable the Development Build option.
Build Use it to build your application.
Build And Run Use it to view the WebGL Player locally. Unity uses a local web server to host your build, and opens it from a localhost URL. Alternatively, you can use a custom local web server with properly configured response headers. For more information, see Compressed builds and server configuration.

For changing the settings for Asset Import Overrides, see Build Settings.

Build Folder

The Build folder contains the following files ([ExampleBuild] represents the name of the target build folder).

File name Contains
[ExampleBuild].loader.js The JavaScript code that the web page needs to load the Unity content.
[ExampleBuild].framework.js JavaScript runtime and plugins.
[ExampleBuild].wasm WebAssembly binary.
[ExampleBuild].mem A binary image to initialize the heap memory for your Player. Unity generates this file for multi-threaded WebAssembly builds only.
[ExampleBuild].data Asset data and ScenesA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary
.
[ExampleBuild].symbols.json Debug symbol names necessary to demangle an error stack trace. This file is only generated for Release builds when you enable the Debug Symbols option (File > Build Settings > Player Settings.)
[ExampleBuild].jpg A background image, which displays while the build is loading. This file is only generated when a Background Image is available in the Player Settings (File > Build Settings > Player Settings > Splash Image). For more information, see Splash Screen.

If you enable a Compression Method for your build, Unity identifies the extension that corresponds with the compression method and adds this extension to the names of the files inside the Build subfolder. If you enable Decompression Fallback, Unity appends the extension .unityweb to the build file names. Otherwise, Unity appends the extension .gz for the Gzip compression method, or .br for the Brotli compression method. For more information, see WebGL: Compressed builds and server configuration.

If you enable Name Files As Hashes in the Player Settings, Unity uses the hash of the file content instead of the default filename. This applies to each file in the build folder. This option allows you to upload updated versions of the game builds into the same folder on the server, and only upload the files which have changed between build iterations.

Note: Opening a Player directly from the file system might not work in some browsers. This is due to security restrictions applied to local file URLs.

Deep Profiling Support

Enable the Deep Profiling Support setting to make the Unity Profiler profile every function call in your application. For more information see the documentation on Deep Profiling.

Enable Exceptions

Open Publishing Settings to access Enable Exceptions. Enable Exceptions allows you to specify how unexpected code behavior (also known as errors) is handled at run time. It has these options:

  • None: Select this if you don’t need any exception support. This gives the best performance and smallest builds. With this option, any exception thrown causes your content to stop with an error in that setting.
  • Explicitly Thrown Exceptions Only (default): Select this to capture exceptions which are explicitly specified from a throw statement in your scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
    See in Glossary
    and to also ensure finally blocks are called. Note that selecting this option makes the generated JavaScript code from your scripts longer and slower; This might only be an issue if scripts are the main bottleneck in your project.
  • Full Without Stacktrace: Select this option to capture: * Exceptions which are explicitly specified from throw statements in your scripts (the same as in the Explicitly Thrown Exceptions Only option)
    • Null References
    • Out of Bounds Array accesses
  • Full With Stacktrace: This option is similar to the option above but it also captures Stack traces. Unity generates these exceptions by embedding checks for them in the code, so this option decreases performance and increases browser memory usage. Only use this for debugging, and always test in a 64-bit browser.

Data Caching

To access Data Caching, go to Publishing Setings via File > Build Settings > Player Settings > WebGL. This enables the browser to cache the main data files into the IndexedDB database.

Using the default browser HTTP cache does not guarantee that the browser caches a particular response. This is because the browser HTTP cache has limited space, and the browser might not be able to cache files that are too large.

To improve your loading speed, IndexedDB allows you to cache files above the browser limit. When you cache more files, you increase the chance that downloaded content is available on the user’s machine during the next run of the build.

Data Caching only caches the .data files in the IndexedDB cache for HTTP responses. To cache AssetBundles, you need to enable Data Caching and override unityInstance.Module.cacheControl(). To do this, make sure Module.cacheControl(url) returns must-revalidate for the requested AssetBundle URL. For example, you can override the unityInstance.Module.cacheControl() function in the fulfillment callback of the Promise that createUnityInstance() returns. For further information on createUnityInstance() see WebGL: Compressed builds and server configuration.

Texture Compression

The texture compression setting in WebGL lets you create builds that target platforms based on the texture compression formats they support. The texture compression format value you set here has priority over the Player settings texture compression format value. To run your game on both desktop and mobile browsers with compressed textures, you might want to create two builds: * Targeting desktop browsers with DXT set as the texture compression format * Targeting mobile browsers with ASTC set as the texture compression format

Create builds for desktop and mobile browsers from a script

You can run a build for both desktop browsers and mobile browsers with the corresponding texture compression formats simultaneously using a script. For example:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;
using System.Diagnostics;
using System.IO;
using UnityEditor.Build.Reporting;

public class comboBuild
{
    //This creates a menu item to trigger the dual builds https://docs.unity3d.com/ScriptReference/MenuItem.html 

    [MenuItem("Game Build Menu/Dual Build")]
    public static void BuildGame()
    {
      //This builds the player twice: a build with desktop-specific texture settings (WebGL_Build) as well as mobile-specific texture settings (WebGL_Mobile), and combines the necessary files into one directory (WebGL_Build)
      
      string dualBuildPath    = "WebGLBuilds";
      string desktopBuildName = "WebGL_Build";
      string mobileBuildName  = "WebGL_Mobile";

      string desktopPath = Path.Combine(dualBuildPath, desktopBuildName);
      string mobilePath  = Path.Combine(dualBuildPath, mobileBuildName);
      string[] scenes = new string[] {"Assets/scene.unity"};

      EditorUserBuildSettings.webGLBuildSubtarget = WebGLTextureSubtarget.DXT;
      BuildPipeline.BuildPlayer(scenes, desktopPath, BuildTarget.WebGL, BuildOptions.Development); 

      EditorUserBuildSettings.webGLBuildSubtarget = WebGLTextureSubtarget.ASTC;
      BuildPipeline.BuildPlayer(scenes,  mobilePath, BuildTarget.WebGL, BuildOptions.Development); 

      // Copy the mobile.data file to the desktop build directory to consolidate them both
      FileUtil.CopyFileOrDirectory(Path.Combine(mobilePath, "Build", mobileBuildName + ".data"), Path.Combine(desktopPath, "Build", mobileBuildName + ".data"));
    }  
}

You can modify the WebGL template’s index.html file to select the appropriate data file if there’s support for the texture compression format extension:

// choose the data file based on whether there's support for the ASTC texture compression format
      var dataFile = "/{{{ DATA_FILENAME }}}";                                  
      var c = document.createElement("canvas");                                 
      var gl = c.getContext("webgl");                                      
      var gl2 = c.getContext("webgl2");                                    
      if ((gl && gl.getExtension('WEBGL_compressed_texture_astc')) || (gl2 &&   
              gl2.getExtension('WEBGL_compressed_texutre_astc'))) {             
        dataFile =  "/WebGL_Mobile.data";                                       
      }                                                                         

      var buildUrl = "Build";
      var loaderUrl = buildUrl + "/{{{ LOADER_FILENAME }}}";                    
      var config = {                                                            
        dataUrl: buildUrl + dataFile,                                           
        frameworkUrl: buildUrl + "/{{{ FRAMEWORK_FILENAME }}}",                 
#if USE_WASM                                                                    
        codeUrl: buildUrl + "/{{{ CODE_FILENAME }}}",                           
#endif                                                                          
#if MEMORY_FILENAME                                                             
        memoryUrl: buildUrl + "/{{{ MEMORY_FILENAME }}}",                       
#endif
#if SYMBOLS_FILENAME                                                            
        symbolsUrl: buildUrl + "/{{{ SYMBOLS_FILENAME }}}",                     
#endif                                                                          
        streamingAssetsUrl: "StreamingAssets",                                
        companyName: {{{ JSON.stringify(COMPANY_NAME) }}},
        productName: {{{ JSON.stringify(PRODUCT_NAME) }}},
      productVersion: {{{ JSON.stringify(PRODUCT_VERSION) }}},                
        showBanner: unityShowBanner,                                            
     };  


  • Removed asm.js linker target in Unity 2019.1
  • Build file updates and Data Caching added in Unity 2020.1
Build and distribute a WebGL application
Reduce load times with AssetBundles