WebGL

Quantum supports multiple platforms, including WebGL, which comes with its unique challenges that developers must be aware of when working with it. This page provides a comprehensive list of these considerations.

WebGL Performance

WebGL is a unique environment that presents certain limitations. In general, performance is expected to be lower compared to other platforms. Hence, it is crucial to test the performance of your application in WebGL builds and not just within the editor to ensure optimal performance.

When the runInBackground option is disabled in the Player Settings, the application will stop running when the player switches to another tab. If the tab remains inactive for an extended period, the client will disconnect and will require reestablishing the connection once the tab is brought back into focus.

Given the low performance of WebGL, it is recommended to use the Quantum release libraries. Select the release libraries with Tools > Quantum > Toggle Debug Dlls > Release, see Release And Debug Builds. The Quantum debug libraries can be extremely slow on WebGL.

Older versions of Unity only support single-threading in WebGL builds, where the simulation is confined to the main thread and the ThreadCount setting in the SimulationConfig is ignored. Starting with Unity 6, multithreading was introduced as an experimental feature and can be enabled through PlayerSettings.

Stack Traces

To enhance WebGL performance in release builds you can turn off the stack trace of logs in Unity. Go to Edit > Project Settings > Player > Other Settings and scroll all the way down to Stack Trace* Set the stack trace of Warning and Log to None.

Async LUT Loading (Quantum 3.0)

Build size is a critical concern when working with WebGL. A significant portion of the Quantum package size comes from the lookup table LUT files, which can be loaded as Addressable assets to reduce the final build size. Follow the steps below to configure the LUT files as Addressables:

Install Addressables

• Open Window > Package Manager.
• Locate Addressables and install it.

Initialize Addressables

• Open Window > Asset Management > Addressables > Groups.
• Click on Create AddressablesSettings.

Mark LUT Files as Addressables

• Move all files from Assets/Photon/Quantum/Resources/LUT to a folder outside of Resources.

• In the inspector, enable the Addressable checkbox.
• Repeat the same procedure for the QuantumLookupTables located at Assets/QuantumUser/Resources: move it outside of Resources and enable the Addressable checkbox in the inspector.

Scripting Define Symbol

• Open Edit > ProjectSettings > Player.
• Make sure the correct platform tab is selected, WebGL settings in this case.
• Add the define QUANTUM_ENABLE_ASYNC_LUT_LOADING on ScriptDefineSymbols list.

Build Addressables Content

• Build the Addressables content with Window > Asset Management > Addressables > Groups > Build > New Build > Default Build Script before every player build, or enable Build Addressables on Player Build in the Addressables settings.
• Without a content build the player cannot load the LUT files at runtime.

WebSockets

Browsers cannot establish direct UDP connections, so WebSockets over TCP are utilized instead. However, TCP's reliable and sequenced transfer protocol can negatively impact gameplay for players with poor network connections. To provide the best player experience, it is recommended to also offer the game as a download.

A warning that the application is switching to WebSockets may appear in the browser, but this can be safely ignored.

Interactive Showcase

Below is a demonstration of a Quantum WebGL build which you can try right now on your web browser.

Open

Many more WebGL demos can be found in our Itch.io page.

Last updated on 06/11/2026