Unity’s Web build target uses IL2CPP to convert C# code to C++ and then compiles it to WebAssembly with Emscripten, producing a .wasm file plus a JavaScript loader and HTML page that runs it in the browser.
At a glance
| Fact | Value | Source |
|---|---|---|
| Unity Web build converts C# via IL2CPP | C# to C++ to Wasm | docs.unity3d.com |
| Unity calls browser JS through | .jslib plugin | docs.unity3d.com |
| Godot 4 calls browser JS through | JavaScriptBridge singleton | docs.godotengine.org |
When you build for the Web platform in Unity, the IL2CPP toolchain converts your C# code to C++, then compiles that C++ to WebAssembly. The output is a .wasm binary, a JavaScript loader, and an HTML page that instantiates and runs the WebAssembly module in the browser. Unity provides support for developing games on the Web platform, and the Player Settings for Web let you configure memory size, compression format and the WebGL renderer used at runtime.
To make your build talk to the surrounding page (ads, save data, platform SDKs), Unity calls browser JavaScript through a .jslib plugin placed in the project, as described in the Unity manual on interacting with browser scripting. Godot’s HTML5 export does the equivalent job with the JavaScriptBridge singleton in Godot 4 (the JavaScript singleton in Godot 3), letting exported games call into page-level JS the same way.
If you’re integrating a third-party SDK across many platforms, writing your own bridge layer for each one gets repetitive. Playgama Bridge ships a Unity plugin that wraps this JS interop for you, alongside plugins for Godot 3/4, Construct 3, GameMaker, Defold, GDevelop, Cocos Creator and Scratch.
Where do I test the WebGL build?
Always test the actual WebGL build in a real browser, not just the editor – Wasm memory limits, threading and browser-specific quirks (Safari in particular) only show up there. Check the browser console for load errors, confirm the .wasm and data files are served with the correct MIME types, and verify compression settings match what your host serves.
Sources
- Unity manual: Web
- Unity manual: interacting with browser scripting
- Godot docs: exporting for the Web
- MDN: WebGL API
- Playgama Bridge SDK getting started
Related questions
Why does Unity use IL2CPP instead of running C# directly in the browser?
Browsers don’t run C#/.NET natively. IL2CPP converts C# to C++, which is then compiled to WebAssembly so it can execute at near-native speed in any modern browser.
Can I call JavaScript functions from Unity C# code?
Yes, through a .jslib plugin file placed in your Unity project’s Plugins folder, as documented in the Unity manual on interacting with browser scripting.
Does Godot use the same WebAssembly approach as Unity?
Yes. Godot’s HTML5 export also compiles to WebAssembly and is now the default way to export Godot games for the web, per the Godot docs.
Last updated: 24 September 2026