> For the complete documentation index, see [llms.txt](https://docs.edgetag.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.edgetag.io/playground/destination.md).

# Destination

A Destination is custom code that behaves like one of our built-in channels. It runs at event time on the EdgeTag edge, at page load in the browser, and optionally via a cron. It can call third-party APIs, read and write your identity graph, store data in its own database, and expose HTTP endpoints on your domain.

Use a Destination when you need something that isn't covered by the channels EdgeTag ships with. Typical examples include forwarding events to an in-house analytics tool, building a warehouse webhook, or exposing a first-party `/api/subscribe` endpoint backed by your own database.

{% hint style="info" %}
If you're modifying events flowing through **existing** channels (dropping, renaming, enriching), use a [Transformation](broken://pages/SbZJG1KnDnq3GEIyi6Vc) instead. Destinations are for creating **new** integrations.
{% endhint %}

{% embed url="<https://www.loom.com/share/9ddb51e5014644d5b2ea9e9f7115dd41>" %}

### What's in a Destination

A Destination is made up of a small set of stage files and, optionally, custom HTTP endpoints:

* **Edge files** — `edge/init`, `edge/tag`, `edge/user`, `edge/scheduled`. Run on the EdgeTag edge (Cloudflare Workers) at their respective lifecycle points.
* **Browser files** — `browser/init`, `browser/tag`, `browser/user`. Run in the visitor's browser alongside the EdgeTag SDK.
* **CDN APIs** — browser-callable HTTP endpoints on your EdgeTag domain.
* **Server APIs** — authenticated server-only HTTP endpoints, with access to the current user.

Only the files you actually write are invoked — leaving a file empty skips that stage entirely.

{% content-ref url="/pages/983b45d97791714f87a341bc60152bcdf2082402" %}
[File Structure](/playground/destination/file-structure.md)
{% endcontent-ref %}

### Capabilities at a glance

From Destination code, you can:

* Make outbound HTTP requests through `params.requestHandler`
* Read and write the EdgeTag identity graph via `params.userSave`, `params.userGet`, and `params.providerSave`
* Persist state in a **D1** database, **KV** store, **R2** bucket, or **Analytics Engine** dataset
* Run **scheduled** jobs on a cron
* Load and initialize third-party scripts in the browser, with full consent awareness
* Expose **custom HTTP endpoints** (authenticated server APIs and browser-callable CDN APIs) on your EdgeTag domain


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