# Script Tag
Add the following tag to your page to load the Allegro SDK:
```html
```
Replace `your-allegro-instance.com` with your Allegro domain.
## How It Works[](#how-it-works "Direct link to How It Works")
`client.js` is a tiny loader script served by Allegro. When it runs, it creates a new `
```
| Property | Type | Description |
| -------- | --------- | -------------------------------------------------------------------------------- |
| `debug` | `boolean` | Enable debug mode. See [Debug Mode](#debug-mode). |
| `apiUrl` | `string` | Override the API base URL. Defaults to the origin of `client.js`. Rarely needed. |
note
Security-sensitive values (`csrfToken`, `tenant`) are always injected by the server and cannot be overridden from the page.
## Attributes[](#attributes "Direct link to Attributes")
| Attribute | Injected automatically | Description |
| -------------------- | ---------------------- | ----------------------------------------------------------------------------------------------------- |
| `data-tenant-config` | Yes | JSON object with tenant settings (enabled login providers, cookie domain, etc.). |
| `data-debug` | No | Enable debug mode. Presence of the attribute (or `="true"`) is enough. See [Debug Mode](#debug-mode). |
| `data-api-url` | No | Override the API base URL. Defaults to the origin of `client.js`. Rarely needed. |
## Debug Mode[](#debug-mode "Direct link to Debug Mode")
Debug mode writes verbose SDK logs to the browser console. Enable it in any of four ways:
**`window.__allegro` (set before the script tag):**
```html
```
**Attribute on the script tag:**
```html
```
**URL parameter** (persisted to `localStorage` for the session):
```text
https://example.com/article?allegro_debug=1
```
Pass `allegro_debug=0` to clear it.
**Browser console** (takes effect immediately, persists across page loads):
```js
window.allegro.debug();
```
## `allegro:ready` Event[](#allegroready-event "Direct link to allegroready-event")
The SDK dispatches `allegro:ready` on `window` once initialization is complete. Use this if you need to interact with the SDK after it has loaded but cannot guarantee the callback queue has been set up:
```js
window.addEventListener('allegro:ready', function () {
window.allegro.push(function (allegro) {
// SDK is ready
});
});
```
For most use cases the [event queue pattern](/developer/platform/event-queue.md) is simpler — callbacks pushed to `window.allegro` before the SDK loads are replayed automatically.
## Embed Snippet[](#embed-snippet "Direct link to Embed Snippet")
Allegro administrators can inject custom JavaScript into every page that loads `client.js` via **Organization Settings → Embed Snippet**. The snippet is appended directly to the loader and executes in the same context as the SDK, after initialization is complete.
A typical snippet uses the [event queue pattern](/developer/platform/event-queue.md) to run code once the SDK is ready:
```js
window.allegro.push((allegro) => {
// Runs after Allegro initializes on every page
});
```
The snippet is served as part of `client.js` and is cached for up to 5 minutes. Changes made in the admin may not appear on your site immediately — allow up to 5 minutes for the cache to expire.
Version history
Every save creates a revision. Administrators can browse diffs and restore any previous version from the Version History panel in the Embed Snippet settings page.
## Async Loading[](#async-loading "Direct link to Async Loading")
The loader script is injected with `async = true` by default so it does not block page rendering. To load the SDK synchronously (for example, in a server-side rendering environment where you need it available before paint), add `?async=false` to the `client.js` URL:
```html
```