# Worth adding preconnect hints for cdn.croct.io and api.croct.io?

Asked by qmarsh on 2026-06-16. Tags: performance, dx, networking.

Doing a resource-hints pass on a client site. Lighthouse flags third-party
origins without preconnect. Which hosts does the Croct SDK actually talk to,
and does preconnecting them shave anything meaningful? Setup varies per client
(some script tag, some npm, one fully server-side) so the answer probably
depends on the mode

## 1 answer

### Answer from Dario Fumagalli (2026-06-17)

It depends entirely on the mode, so here is the host map.

No-code script tag: the script loads from `cdn.croct.io` and API calls go to
`api.croct.io`. Those are the two hosts in play, and preconnect helps most
when the first fetch happens early in the page life, which is typical since
the SDK starts talking as soon as it plugs. Worth adding both hints on those
clients:

```html
<link rel="preconnect" href="https://cdn.croct.io" />
<link rel="preconnect" href="https://api.croct.io" />
```

npm SDK: there is no CDN script at all, the code ships in your bundle, so
only `api.croct.io` is relevant and only if the page fetches content or
tracks from the client.

Fully server-side (`fetchContent`): the browser never talks to Croct. The
server makes the calls, so there is nothing to preconnect and Lighthouse has
nothing to flag. Skip the hints on that client.

One more configuration to know about: if a client uses first-party proxying
via `baseEndpointUrl` and `cidAssignerEndpointUrl`, requests ride the
existing connection to your own origin. No extra hints needed there either,
and as a side effect that setup also neutralizes ad-blocker filtering of the
SDK endpoints.