[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [local‑first/Owner](https://evolu.dev/docs/api-reference/common/local-first/Owner) › parseOwnerIdFromOwnerWebSocketTransportUrl

```ts
function parseOwnerIdFromOwnerWebSocketTransportUrl(
  url: string,
): (string & Brand<"Id"> & Brand<"OwnerId">) | null;
```

Defined in: [packages/common/src/local-first/Owner.ts:398](https://github.com/evoluhq/evolu/blob/e7144e2bbe9069362b62dec1b64a8aa922b8f1b0/packages/common/src/local-first/Owner.ts#L398)

Extracts [OwnerId](https://evolu.dev/docs/api-reference/common/local-first/Owner/variables/OwnerId) from an [OwnerWebSocketTransport](https://evolu.dev/docs/api-reference/common/local-first/Owner/interfaces/OwnerWebSocketTransport) URL query
string.

Parses the query string `?ownerId=...` and validates that the extracted value
is a valid [OwnerId](https://evolu.dev/docs/api-reference/common/local-first/Owner/variables/OwnerId).

### Example

```ts
parseOwnerIdFromOwnerWebSocketTransportUrl("/sync?ownerId=_12345678abcdefgh");
// Returns: OwnerId or null
```