> ## 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.

# Supporting New Chains

> Configure CosmJS for new Cosmos SDK chains with custom prefixes, gas prices, and account types

Connecting to a new Cosmos SDK chain typically involves configuring a few chain-specific parameters. CosmJS auto-detects the CometBFT version (0.37, 0.38, or 1.x), so transport setup is usually automatic.

## Chain Configuration

The minimum configuration you need for a new chain:

```typescript theme={"system"}
import { DirectSecp256k1HdWallet } from "@cosmjs/proto-signing";
import { SigningStargateClient, GasPrice } from "@cosmjs/stargate";

const chainConfig = {
  rpcEndpoint: "https://rpc.my-chain.network",
  prefix: "mychain",
  denom: "umytoken",
  gasPrice: "0.01umytoken",
};

const wallet = await DirectSecp256k1HdWallet.fromMnemonic(mnemonic, {
  prefix: chainConfig.prefix,
});

const client = await SigningStargateClient.connectWithSigner(
  chainConfig.rpcEndpoint,
  wallet,
  { gasPrice: GasPrice.fromString(chainConfig.gasPrice) },
);
```

The key parameters are:

| Parameter     | Purpose                     | Example                          |
| ------------- | --------------------------- | -------------------------------- |
| `rpcEndpoint` | CometBFT/Tendermint RPC URL | `"https://rpc.my-chain.network"` |
| `prefix`      | Bech32 address prefix       | `"osmo"`, `"cosmos"`, `"juno"`   |
| `denom`       | Fee token denomination      | `"uosmo"`, `"uatom"`             |
| `gasPrice`    | Price per gas unit          | `"0.025uosmo"`                   |

## Chains with Custom Modules

Most application-specific chains (Osmosis, dYdX, Stride, etc.) define custom modules beyond the standard Cosmos SDK set. Register their types and converters as described in the [Custom Modules](/cosmjs/v0.38.x/guides/extending/custom-modules) guide:

```typescript theme={"system"}
import { Registry } from "@cosmjs/proto-signing";
import {
  SigningStargateClient,
  GasPrice,
  AminoTypes,
  defaultRegistryTypes,
  createDefaultAminoConverters,
} from "@cosmjs/stargate";

const registry = new Registry([
  ...defaultRegistryTypes,
  ...myChainModuleATypes,
  ...myChainModuleBTypes,
]);

const aminoTypes = new AminoTypes({
  ...createDefaultAminoConverters(),
  ...createModuleAAminoConverters(),
  ...createModuleBAminoConverters(),
});

const client = await SigningStargateClient.connectWithSigner(
  "https://rpc.my-chain.network",
  wallet,
  { registry, aminoTypes, gasPrice: GasPrice.fromString("0.01utoken") },
);
```

<Tip>
  Many popular chains have pre-built TypeScript libraries generated with Telescope: [OsmoJS](https://github.com/osmosis-labs/osmojs) for Osmosis, [stargazejs](https://github.com/public-awesome/stargazejs) for Stargaze, [stridejs](https://github.com/Stride-Labs/stridejs) for Stride, and others. Check if one exists for your chain before writing custom module code.
</Tip>

## Custom Account Parsers

Some chains use non-standard account types (e.g. `EthAccount` on EVM-compatible chains). The default `accountFromAny` parser won't recognize them, causing account lookups to fail. Pass a custom `accountParser` to handle these:

```typescript theme={"system"}
import { decodePubkey } from "@cosmjs/proto-signing";
import { accountFromAny, AccountParser } from "@cosmjs/stargate";
import { EthAccount } from "./generated/ethermint/types/v1/account";
import { Any } from "cosmjs-types/google/protobuf/any";

const customAccountParser: AccountParser = (any: Any) => {
  if (any.typeUrl === "/ethermint.types.v1.EthAccount") {
    const ethAccount = EthAccount.decode(any.value);
    const baseAccount = ethAccount.baseAccount;
    if (!baseAccount) throw new Error("EthAccount missing baseAccount");
    return {
      address: baseAccount.address,
      pubkey: baseAccount.pubKey ? decodePubkey(baseAccount.pubKey) : null,
      accountNumber: Number(baseAccount.accountNumber),
      sequence: Number(baseAccount.sequence),
    };
  }
  return accountFromAny(any);
};

const client = await SigningStargateClient.connectWithSigner(
  "https://rpc.my-chain.network",
  wallet,
  { accountParser: customAccountParser },
);
```

The `accountParser` option is available on both `StargateClient` (read-only) and `SigningStargateClient` (signing). The parser receives an `Any`-encoded account from the auth module and must return an `Account` object with `address`, `pubkey`, `accountNumber`, and `sequence`.

## HD Derivation Paths

Different chains may use different [BIP-44](https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki) coin types in their HD derivation path. The default is `m/44'/118'/0'/0/0` (coin type 118, the Cosmos Hub standard). Override this for chains that use a different coin type:

```typescript theme={"system"}
import { DirectSecp256k1HdWallet } from "@cosmjs/proto-signing";
import { stringToPath } from "@cosmjs/crypto";

const wallet = await DirectSecp256k1HdWallet.fromMnemonic(mnemonic, {
  prefix: "evmos",
  hdPaths: [stringToPath("m/44'/60'/0'/0/0")],
});
```

Common coin types:

| Chain                             | Coin Type | HD Path             |
| --------------------------------- | --------- | ------------------- |
| Cosmos Hub, most Cosmos chains    | 118       | `m/44'/118'/0'/0/0` |
| Ethereum-based (Evmos, Injective) | 60        | `m/44'/60'/0'/0/0`  |
| Terra                             | 330       | `m/44'/330'/0'/0/0` |
| Crypto.org                        | 394       | `m/44'/394'/0'/0/0` |

```typescript theme={"system"}
import { stringToPath } from "@cosmjs/crypto";

const cosmosPath = stringToPath("m/44'/118'/0'/0/0");
const ethPath = stringToPath("m/44'/60'/0'/0/0");
```

## Multiple Accounts

To derive multiple accounts from the same mnemonic, pass multiple HD paths:

```typescript theme={"system"}
import { DirectSecp256k1HdWallet } from "@cosmjs/proto-signing";
import { stringToPath } from "@cosmjs/crypto";

const wallet = await DirectSecp256k1HdWallet.fromMnemonic(mnemonic, {
  prefix: "cosmos",
  hdPaths: [
    stringToPath("m/44'/118'/0'/0/0"),
    stringToPath("m/44'/118'/0'/0/1"),
    stringToPath("m/44'/118'/0'/0/2"),
  ],
});

const accounts = await wallet.getAccounts();
// accounts[0], accounts[1], accounts[2] — each with a different address
```

## Next Steps

<CardGroup cols={2}>
  <Card title="Custom Modules" icon="puzzle-piece" href="/cosmjs/v0.38.x/guides/extending/custom-modules">
    Build a complete module integration for your chain's custom message types.
  </Card>

  <Card title="Code Generation" icon="wand-magic-sparkles" href="/cosmjs/v0.38.x/guides/extending/code-generation">
    Use Telescope or ts-proto to generate TypeScript types from your chain's protobuf definitions.
  </Card>

  <Card title="Cosmos EVM Chains" icon="ethereum" href="/cosmjs/v0.38.x/concepts/cosmos-evm/key-differences">
    Special considerations for EVM-compatible Cosmos chains.
  </Card>
</CardGroup>