Godot 4’s HTML5 export uses WebAssembly, WebGL, and SharedArrayBuffers. Browsers require a secure context for these features to be available, which requires sending certain HTTP headers when serving the game content. For development, there are two straight-forward ways to serve the content: Godot’s Python http server and Miniserve.

Godot’s Python HTTP Server

The Godot team has written a script, leveraging Python’s existing http server implementation, which adds the necessary HTTP headers.

Download serve.py

Run it via:

python3 serve.py -r game_directory

Miniserve

Miniserve is a self-contained command-line tool for serving HTTP content. As a self-contained binary, it may be easier to install and manage than a full Python installation.

You can run it via:

./miniserve --header Cross-Origin-Embedder-Policy:require-corp --header Cross-Origin-Opener-Policy:same-origin game_directory