Platform: Web Browser API integration, LocalStorage persistence, and size optimization define web deployment. Available Scripts web_bridge_sync.gd Expert JavaScriptBridge helpers for browser API integration (persistence, analytics). NEVER Do in Web Development NEVER use FileAccess for saves — FileAccess.open("user://save.dat") on web? Browser sandbox blocks filesystem. Use JavaScriptBridge + localStorage. NEVER forget loading screen — 20MB wasm download with default load screen = user closes tab. MUST customize index.html with progress bar + brand assets. NEVER use threads — Thread.new() on web? Not supported. Use await for async OR split work across frames with await get_tree().process_frame . NEVER ignore HTTPS requirement — Geolocation, microphone, webcam APIs REQUIRE HTTPS. Local http:// = APIs blocked. Use localhost OR HTTPS. NEVER exceed 50MB build size — 100MB WebAssembly = user rage-quits during load. Compress textures (ETC2/ASTC), exclude unused assets. NEVER hardcode window size — get_viewport().size = Vector2(1920, 1080) on web? Breaks mobile browsers. Use get_window().size_changed + responsive UI.

< div id = " loading-screen "

< div class = " progress-bar "

< div id = " progress " style = " width : 0 % "

</ div

</ div

< p id = " status-text "

Loading... </ p

</ div

< script

const engine = new Engine ( CONFIG ) ; engine . startGame ( { onProgress : function ( current , total ) { const percent = Math . floor ( ( current / total ) * 100 ) ; document . getElementById ( 'progress' ) . style . width = percent + '%' ; document . getElementById ( 'status-text' ) . innerText = Loading ${ percent } % ; } } ) . then ( ( ) => { document . getElementById ( 'loading-screen' ) . style . display = 'none' ; } ) ; </ script

Browser Integration

Check if running in browser

if OS . has_feature ( "web" ) :

Web-specific code

JavaScriptBridge . eval ( "console.log('Running in browser')" ) LocalStorage Save func save_to_browser ( ) -> void : if not OS . has_feature ( "web" ) : return var data := JSON . stringify ( get_save_data ( ) ) JavaScriptBridge . eval ( "localStorage.setItem('savegame', '%s')" % data ) func load_from_browser ( ) -> Dictionary : if not OS . has_feature ( "web" ) : return { } var data_str := JavaScriptBridge . eval ( "localStorage.getItem('savegame')" ) if data_str : return JSON . parse_string ( data_str ) return { } Size Optimization

Minimize build size

[ rendering ] textures/vram_compression/import_s3tc_bptc = false textures/vram_compression/import_etc2_astc = true

Exclude unnecessary exports

[ export_preset ] exclude_filter = " .md,.txt,docs/* " Performance Target 60 FPS on mid-range browsers Limit godot-particles - WebGL has lower limits Reduce draw calls Avoid large textures Best Practices Loading Screen - Users expect feedback File Size - Keep under 50MB Mobile Web - Test on phones HTTPS - Required for many APIs Reference Related: godot-export-builds , godot-platform-mobile Related Master Skill: godot-master