> ## Documentation Index
> Fetch the complete documentation index at: https://cosmos-docs-cosmjs-docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom Query Extensions

> Write your own query extensions for custom chain modules and integrate them with QueryClient

If your chain has custom modules, you can write your own query extensions that integrate seamlessly with `QueryClient`. This works with or without protobuf definitions.

## From Protobuf Definitions

If you have generated TypeScript types from your `.proto` files (using `ts-proto` or similar), wire them up with `createProtobufRpcClient`:

```typescript theme={"system"}
import { createProtobufRpcClient, QueryClient } from "@cosmjs/stargate";
import { QueryClientImpl } from "./generated/mymodule/query";

export interface MyModuleExtension {
  readonly mymodule: {
    readonly myQuery: (param: string) => Promise<MyQueryResponse>;
  };
}

export function setupMyModuleExtension(base: QueryClient): MyModuleExtension {
  const rpc = createProtobufRpcClient(base);
  const queryService = new QueryClientImpl(rpc);

  return {
    mymodule: {
      myQuery: async (param: string) => {
        return queryService.MyQuery({ param });
      },
    },
  };
}
```

## Using the Extension

Compose your custom extension alongside built-in ones:

```typescript theme={"system"}
import { QueryClient, setupBankExtension } from "@cosmjs/stargate";
import { connectComet } from "@cosmjs/tendermint-rpc";

const cometClient = await connectComet("https://rpc.my-chain.network");
const queryClient = QueryClient.withExtensions(
  cometClient,
  setupBankExtension,
  setupMyModuleExtension,
);

const result = await queryClient.mymodule.myQuery("cosmos1senderaddress...");
```

## Without Protobuf Definitions

You can also query any ABCI path directly using the raw query interface:

```typescript theme={"system"}
import { connectComet } from "@cosmjs/tendermint-rpc";
import { QueryClient } from "@cosmjs/stargate";

const cometClient = await connectComet("https://rpc.my-chain.network");
const queryClient = new QueryClient(cometClient);

const response = await queryClient.queryAbci(
  "/my.custom.module.Query/MyMethod",
  encodedRequest,
);
```

## Next Steps

<CardGroup cols={2}>
  <Card title="Querying Overview" icon="magnifying-glass" href="/cosmjs/v0.38.x/guides/query/querying">
    All built-in query extensions.
  </Card>

  <Card title="CosmWasm Queries" icon="file-code" href="/cosmjs/v0.38.x/guides/query/cosmwasm">
    Smart contract queries using the wasm extension.
  </Card>
</CardGroup>