The core set is Canvas/WebGL for rendering, Web Storage (and IndexedDB) for saving progress, WebSockets for multiplayer, and the Ad Placement API (adBreak) for ads. Which ones you need depends on whether the game is 2D, needs a server, or needs to persist state.
At a glance
| Fact | Value | Source |
|---|---|---|
| 2D/3D rendering API for canvas graphics | Canvas API / WebGL | developer.mozilla.org |
| Client-side save data persistence | Web Storage API | developer.mozilla.org |
| Full-duplex connection for real-time multiplayer | WebSockets API | developer.mozilla.org |
For most browser games the useful set is small: a rendering API, a storage API, and (if the game is multiplayer or monetized) a networking or ad API. Pick based on what the game actually does.
For ad calls specifically, a single SDK is often easier than wiring adBreak by hand across engines: Playgama Ad connects one SDK to 11 demand partners, including Google Ad Manager, for interstitial, rewarded, banner and in-page video.
- Canvas API / WebGL – 2D games draw to a
<canvas>context; 3D or shader-heavy games use WebGL directly or through an engine. MDN’s game development section has a reference for the most common APIs used across genres. - Web Storage API –
localStorage/sessionStoragefor simple save data. Note that in a private window this data is deleted when the tab or browser closes, so do not rely on it for anything critical without a server backup. - WebSockets API – a persistent, full-duplex connection, the standard choice for real-time multiplayer state sync instead of polling.
- Ad Placement API (adBreak) – if you monetize with Google AdSense H5 Games Ads, you call
adBreak()at natural pauses to show interstitial or rewarded ads; Google applies a frequency cap automatically and returnsfrequencyCappedinbreakStatus.
Engines wrap these APIs rather than replacing them. Unity WebGL builds reach browser JavaScript through a .jslib plugin; Godot 4 web exports use the JavaScriptBridge singleton. Both exist because the engine doesn’t expose every browser feature by default, so you write a small interop layer to call things like storage, ads or platform SDKs.
Where to publish once the game runs: Poki, CrazyGames, GameDistribution, itch.io, and playgama.com, where developers upload via the Developer Console and get feedback within 24 hours before the game is distributed to partner portals.
Sources
- MDN: WebGL API
- Unity manual: interacting with browser scripting
- Godot docs: exporting for the Web
- Playgama Bridge docs
Related questions
Do I need WebSockets for a simple single-player game?
No. WebSockets matter only for real-time multiplayer or live server sync. A single-player game just needs a rendering API and Web Storage for saves.
Should I call browser APIs directly or through my engine?
Use the engine’s interop layer (Unity .jslib, Godot JavaScriptBridge) so calls stay consistent across builds, rather than hand-writing browser API calls per platform.
Last updated: 24 September 2026