> For the complete documentation index, see [llms.txt](https://developer.nexx360.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.nexx360.io/miscellaneous/prebid-video-cache.md).

# Prebid Video Cache

Nexx360 operates a hosted, [Prebid Cache](https://github.com/prebid/prebid-cache)-compatible service that stores winning VAST creatives at auction time and serves them back to video players via a short URL. The public endpoint is `https://fast.nexx360.io/pb/cache`.

It is a drop-in replacement for the legacy AppNexus Prebid Cache (`https://prebid.adnxs.com/pbc/v1/cache`) — only the `cache.url` value in your Prebid.js configuration changes.

## Why a video cache?

Most ad servers (Google Ad Manager in particular) and most video players accept a VAST **URL**, not raw VAST XML. Header bidding produces VAST creatives at auction time, so Prebid.js needs somewhere addressable to park them before passing a reference to the ad server.

The end-to-end flow:

1. A bidder returns a VAST XML payload to Prebid.js.
2. Prebid.js `POST`s the VAST to `https://fast.nexx360.io/pb/cache` and receives a UUID.
3. The UUID is written into GAM key-values (`hb_uuid`, `hb_cache_id`, `hb_cache_host`, `hb_cache_path`).
4. The GAM video creative builds a cache URL (`https://fast.nexx360.io/pb/cache/XXXX?uuid=…`) and serves it to the player.
5. The player issues a `GET` on the cache URL to retrieve the VAST XML and start playback.

See the [Prebid video overview](https://docs.prebid.org/prebid-video/video-overview.html) for the canonical explanation.

{% hint style="info" %}
If a bidder caches its own creative and returns `bidResponse.videoCacheKey`, Prebid skips the cache step for that bid. The cache is only used for bidders that hand back raw VAST.
{% endhint %}

## Configure Prebid.js

Set the cache URL in `pbjs.setConfig`:

```javascript
pbjs.setConfig({
    cache: {
        url: 'https://fast.nexx360.io/pb/cache/XXXX'
    }
});
```

Replace `XXXX` with your Nexx360 account ID.

{% hint style="info" %}
Pass your account ID as a **path segment** (`/pb/cache/XXXX`), not as a query parameter. Prebid.js appends `?uuid=…` to `cache.url` when it builds the retrieval URL, so a query-string form such as `?account_id=XXXX` would produce an invalid double-query URL (`…?account_id=XXXX?uuid=…`). The path form keeps the appended `?uuid=…` valid.

`account_id` is a tagging convention used for log correlation across the Nexx360 stack. The cache service itself does not validate it, but you should still include it so support can trace your traffic.
{% endhint %}

Other useful options on the `cache` config object:

| Option                 | Description                                                                       |
| ---------------------- | --------------------------------------------------------------------------------- |
| `ignoreBidderCacheKey` | Force re-wrapping of bidder-supplied keys so every VAST sits behind one cache URL |
| `useLocal`             | Store VAST as a browser blob instead of calling the remote cache                  |
| `batchSize`            | Batch multiple puts into a single POST                                            |
| `batchTimeout`         | Maximum wait time in ms before flushing a batch                                   |
| `timeout`              | Request timeout in ms                                                             |

Full reference: [Prebid.js `setConfig`](https://docs.prebid.org/dev-docs/publisher-api-reference/setConfig.html#setConfig-vast-cache).

## Retrieving cached VAST in GAM creatives

The cache URL pattern used in GAM creatives (`hb_cache_host` + `hb_cache_path` + `hb_cache_id`) is documented in the GAM setup pages alongside the full creative snippet:

{% content-ref url="/pages/qK2DpS7MrAHHnXkMq8i6" %}
[Google Ad Manager Setup](/integration-methods/direct-inapp-sdkless/google-ad-manager-setup.md)
{% endcontent-ref %}

For questions about cache configuration or migration from AppNexus, contact <tech@nexx360.io>.


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