Web technology imposes restrictions on Unity web applications designed to run in web browsers. Make sure you’re aware of the following technical limitations before you build your application for the Web platform.
Most popular desktop browser versions support Unity Web content, but do note that different browsers offer different levels of support.
The following features in Web builds are either not available or limited due to constraints of the platform itself:
Debugging Web builds isn’t supported in Visual Studio. For more information, refer to Debug and troubleshoot Web builds.
Web builds don’t support the Unity Cache and Caching Scripting API due to restricted access to the filesystem in browsers. Network requests to asset data and AssetBundles are instead cached in the browser cache. Refer to Cache behavior in Web.
The Web platform doesn’t support physical-to-active keyboard mapping, a feature of Unity’s Input System. This limitation means that certain InputControl properties that rely on translating physical key codes to a virtual keyboard layout don’t function as expected with non-English keyboards.
Managed (C#) threads aren’t supported on the Web platform due to the lack of a multithreaded garbage collection feature in WebAssembly.
However, Unity provides multithreading support for native C/C++ engine code and for C# jobs compiled with the Burst compiler.
For more details about multithreading, refer to Multithreading in Unity Web.
There are a few networkingThe Unity system that enables multiplayer gaming across a computer network. More info
See in Glossary features that Web platform doesn’t support:
Browsers don’t allow direct access to IP sockets for networking due to security concerns. For more information, refer to Web networking.
.NET networking classes within the System.Net namespace aren’t supported.
Web platform doesn’t support native socket access because of security limitations within browsers. Therefore, Web also doesn’t support features like ICMP ping or UnityEngine.Ping.
There are some limitations in Web platform with the WebGLA JavaScript API that renders 2D and 3D graphics in a web browser. The Unity Web 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 graphics API, which is based on the functionality of the OpenGL ES graphics library. For more information, refer to Web graphics.
Web builds use a custom back end for audio based on the Web Audio API, but it only supports the basic audio functionality. For more information, refer to Audio in Web.
Web is an AOT platform, so it doesn’t allow dynamic generation of code using System.Reflection.Emit. This is the same on all other IL2CPPA Unity-developed scripting back-end which you can use as an alternative to Mono when building projects for some platforms. More info
See in Glossary platforms, iOS, and most consoles.
Unity uses a web server with only basic functionality to host web builds created with Build and Run (menu: Edit > Build Profiles > Build and Run).
The server doesn’t support data caching, which affects:
.data file, which includes all 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