Web Playground
A static playground for learning what the browser you are using can actually do.
Site URL: https://web-playground.xn--uist1idrju3i.jp (custom-domain DNS and Pages settings are owner-managed).
Choose a path
Apps
- Browser Features (
/browser-features/) — measured capability support, permission-policy information, and WebAssembly probes.
- Baked Mochocho (
/baked-mochocho/) — a griddle-cake game with a Rust/WebAssembly physics simulation, WebGPU rendering with a WebGL2 fallback, synthesized Web Audio, and HMAC-signed saves. See the app guide.
- たのしい都道府県つみき (
/tsumiki/) — a physics stacking toy: drop all 47 prefecture blocks (Natural Earth shapes, public domain) onto a torii pedestal with Rapier (WASM) physics, a WebGL2/WebGPU procedural scene, an adaptive WebAudio score, and WebCrypto HMAC-signed saves.
Quick start
Requires Node.js 24.21.0 (see .nvmrc).
nvm install
nvm use
npm ci --ignore-scripts
npm audit signatures
npm run serve
Open http://127.0.0.1:4173. Run npm test for lint, security and documentation gates, generated-file checks, unit tests, Chromium/WebKit/Firefox E2E, and the servoshell WebDriver checks (node scripts/fetch-servo.mjs installs the pinned Servo build first; the suite skips with a reason when it is absent).
Support summary
Capability results are measured at runtime and may be supported, partial, unsupported, or untestable. Layer 1 WebAssembly execution probes currently measure Chromium 17/17, Firefox 15/17 (relaxed SIMD and JSPI absent), WebKit 13/17 (relaxed SIMD, memory64, multi-memory, and JSPI absent), and servoshell 16/17 (shared-memory WebAssembly threads absent). See browser support for caveats and device guidance.
Security and external resources
Security and stability come before runtime performance. Pages load JavaScript and CSS only from their own origin or version-pinned, SRI-protected cdnjs URLs. Static parser checks, runtime browser tests, a locked CSP test, and CodeQL enforce the policy. Navigation links may point elsewhere; they do not load resources. Fonts use system stacks by default. See external-resource policy and SECURITY.md.
Documentation
See the documentation index for persona-based reading order, architecture, WebAssembly, WebMCP, hosting, support, and troubleshooting.
Limitations
- Physical devices are not comprehensively tested; desktop engine results are not a substitute.
- WebMCP is experimental and may not be available in every Chromium build.
- Device APIs may require a secure context, a user gesture, or permission; the app does not prompt on page load.
- The custom domain, DNS, Pages project, and owner-side repository settings must be configured by the repository owner.
License
BSD 3-Clause. See LICENSE.
