## Support for the “extensions” field in GraphQL Request JSON Payloads

### For Query and Mutation

Cosmo Router supports sending the “extensions” field to Subgraphs. If a client sends an “extensions” field alongside a Query or Mutation, or alternatively as part of the “payload” of a Subscription Request, Cosmo Router will by default include the “extensions” field in all Subgraph requests. This feature allows you to extend GraphQL in a very flexible way as defined by the [GraphQL over HTTP specification](https://github.com/graphql/graphql-over-http/blob/main/spec/GraphQLOverHTTP.md#request-parameters). Here’s an example on how this can be used:

```
{\"query\":\"{hello}\",\"extensions\":{\"token\":\"asd\"}}
```

### For initiating a subscription

Alternatively, this feature could be useful to send a token when initiating a subscription:

```
{\"id\":\"1\",\"type\":\"subscribe\",\"payload\":{\"extensions\":{\"token\":\"asd\"},\"query\":\"subscription {\n  currentTime {\n    unixTime\n  }\n}\"}}
```

More info on how this can be used with subscriptions can be found [here](https://cosmo-docs.wundergraph.com/router/subscriptions#using-the-extensions-field).