Omeka S Playground

Live demo · Documentation · Blueprints

Run a full Omeka S site in the browser — no server required.

Omeka S Playground runs Omeka S entirely in the browser using WebAssembly, powered by WordPress Playground's @php-wasm/web runtime. Every page load boots a fresh Omeka S instance — nothing is stored on disk and nothing leaves your browser.

Getting Started

Try it online

Open the live demo — no install needed.

Run it locally

git clone https://github.com/ateeducacion/omeka-s-playground.git
cd omeka-s-playground
make up

Then open http://localhost:8080.

Prerequisites

• Node.js 18+
• npm
• Composer
• Git

How It Works

index.html          Shell UI (toolbar, address bar, log panel)
  └─ remote.html    Runtime host — registers the Service Worker
       ├─ sw.js     Intercepts requests → routes to PHP worker
       └─ php-worker.js (bundled via esbuild)
            └─ @php-wasm/web (WebAssembly, PHP 8.1–8.5)
                 ├─ Omeka core in writable MEMFS  (extracted from ZIP bundle)
                 └─ In-memory state                (SQLite + config + files in MEMFS)

1. The shell boots a scoped runtime host inside an iframe.
2. The Service Worker intercepts all requests under /playground/<scope>/<runtime>/….
3. The PHP worker extracts the Omeka ZIP bundle into writable MEMFS.
4. Omeka runs against an in-memory SQLite database — fully ephemeral, no persistence.
5. If the PHP runtime crashes (WASM OOM / file descriptor exhaustion), the worker snapshots the DB and addon files, boots a fresh runtime, and restores state automatically.

Default credentials: admin@example.com / password (configurable in playground.config.json).

No persistence by design

All state lives in memory (Emscripten MEMFS). Closing the tab destroys everything. This is intentional — the playground is meant for exploration, demos, and testing, not for storing data.

PHP version selection

The settings panel (⚙️ icon) lets you switch between PHP 8.1, 8.2, 8.3 (default), 8.4, and 8.5. Changing PHP version resets the playground to a clean install.

Make targets

Command	Description
make up	Install deps, build the Omeka bundle, and serve locally
make prepare	Install npm deps, vendor browser assets, and bundle the PHP worker
make bundle	Fetch Omeka, run Composer, build the ZIP bundle and manifest
make serve	Start the local dev server on port 8080, including the addon download proxy
make test	Run unit tests
make lint	Check code with Biome
make format	Auto-fix code with Biome
make clean	Remove generated bundle, dist, and vendored runtime assets

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Blueprints

Blueprints are JSON files that describe the desired state of a playground instance — similar to WordPress Playground Blueprints.

A default blueprint is bundled at assets/blueprints/default.blueprint.json. You can override it by:

• Passing ?blueprint=/path/to/file.json in the URL.
• Passing ?blueprint-data=... in the URL with a base64url-encoded UTF-8 JSON blueprint payload.
• Importing a .json file from the toolbar.

What blueprints can configure

• Landing page, installation title, locale, and timezone
• Debug mode for Omeka/PHP error visibility
• Admin and additional users
• A default site with a theme selection
• Item sets and items with remote media
• Module installation/activation from bundled addons, direct ZIP URLs, or omeka.org slugs
• Theme installation from bundled addons, direct ZIP URLs, or omeka.org slugs

Example

{
  "$schema": "./assets/blueprints/blueprint-schema.json",
  "debug": { "enabled": true },
  "landingPage": "/s/demo",
  "siteOptions": {
    "title": "Demo Omeka",
    "locale": "es",
    "timezone": "Atlantic/Canary"
  },
  "users": [
    { "username": "admin", "email": "admin@example.com", "password": "password", "role": "global_admin" }
  ],
  "modules": [
    { "name": "CSVImport", "state": "activate" },
    {
      "name": "Mapping",
      "state": "activate",
      "source": { "type": "url", "url": "https://example.com/Mapping.zip" }
    }
  ],
  "itemSets": [{ "title": "Demo Collection" }],
  "items": [
    {
      "title": "Landscape sample",
      "itemSets": ["Demo Collection"],
      "media": [{ "type": "url", "url": "https://example.com/photo.jpg", "title": "Photo" }]
    }
  ],
  "site": {
    "title": "Demo Site",
    "slug": "demo",
    "theme": "default",
    "setAsDefault": true
  }
}

The full schema is at assets/blueprints/blueprint-schema.json.

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Key Technologies

Technology	Role
@php-wasm/web	PHP 8.1–8.5 compiled to WebAssembly (WordPress Playground runtime)
Omeka S (SQLite branch)	The digital collections platform being served
Service Workers	Intercept HTTP requests and route them to the WASM runtime
esbuild	Bundles the PHP worker and @php-wasm dependencies
fflate	ZIP extraction for the Omeka core bundle

The Omeka source is built from the feature/experimental-sqlite-support branch of ateeducacion/omeka-s.

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Known Limitations

• Remote addon installation only supports ZIP packages that are already ready to run in Omeka. Releases that require Composer, Node builds, or extra post-install steps are not supported in-browser.
• omeka.org slug resolution depends on the current HTML download links on omeka.org.
• Remote ZIP downloads need a proxy endpoint when the upstream host does not expose CORS headers.
• PHP outbound HTTP is limited by the configured outboundHttp.allowedHosts and allowedMethods.
• Browser compatibility is focused on Chromium; Firefox and Safari may need additional validation.
• All state is ephemeral — closing the tab destroys everything.

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Prior Art

• WordPress Playground — the original inspiration for running a PHP CMS entirely in the browser.
• Moodle Playground — sister project running Moodle in the browser with the same architecture.

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Contributing

Contributions are welcome. Open an issue or submit a pull request.

License

See the repository for license details.