Create and configure an XMTP client

The XMTP message API revolves around a network client that allows retrieving and sending messages to other network participants.

Create a client

To create an XMTP client, it must be connected to a wallet on startup. You must pass in a connected wallet that implements the Signer interface. This wallet is required for authentication and encryption purposes.

For more information about wallet signature requests, see Account signatures.

Clients created by XMTP v3 SDKs can also support XMTP v2 messages if the wallet is an EOA. At a high-level, XMTP v3 is used to support group chat and XMTP v2 is used to support 1:1 chat.

In the near future, XMTP v3 will support both group and 1:1 chat with Messaging Layer Security (MLS). Have questions or feedback? Post to the XMTP Community Forums.

Group chat is currently supported in Kotlin, Swift, React Native, and Node.js.

In the near future, XMTP v3 will also support group chat for the web.

For more information about the work being done to support group chat for the web, see this SQLite, WebAssembly, and Diesel talk in the XMTP Developer Community Call.

If your mobile app provides group chat, you must explicitly configure your client to enable this functionality by setting the enableV3 client option to true.

For more information about client options, including how to set your client's network environment, see client configuration options.

import { Client } from "@xmtp/xmtp-js";
 
// Create the client with a `Signer` from your application
const xmtp = await Client.create(signer, {
  env: "production",
});

Saving keys

You can export the unencrypted key bundle using the static method getKeys, save it somewhere secure, and then provide those keys at a later time to initialize a new client using the exported XMTP identity.

// Get the keys using a valid Signer. Save them somewhere secure.
import { loadKeys, storeKeys } from "./helpers";
const clientOptions = {
  env: "production",
};
 
let keys = loadKeys(address);
if (!keys) {
keys = await Client.getKeys(signer, {
...clientOptions,
// we don't need to publish the contact here since it
// will happen when we create the client later
skipContactPublishing: true,
// we can skip persistence on the keystore for this short-lived
// instance
persistConversations: false,
});
storeKeys(address, keys);
}
const client = await Client.create(null, {
...clientOptions,
privateKeyOverride: keys,
});
 

// Create a client using keys returned from getKeys
const ENCODING = "binary";
 
export const getEnv = (): "dev" | "production" | "local" => {
  return "production";
};
 
export const buildLocalStorageKey = (walletAddress: string) =>
  walletAddress ? `xmtp:${getEnv()}:keys:${walletAddress}` : "";
 
export const loadKeys = (walletAddress: string): Uint8Array | null => {
  const val = localStorage.getItem(buildLocalStorageKey(walletAddress));
  return val ? Buffer.from(val, ENCODING) : null;
};
 
export const storeKeys = (walletAddress: string, keys: Uint8Array) => {
  localStorage.setItem(
    buildLocalStorageKey(walletAddress),
    Buffer.from(keys).toString(ENCODING),
  );
};
 
export const wipeKeys = (walletAddress: string) => {
  // This will clear the conversation cache + the private keys
  localStorage.removeItem(buildLocalStorageKey(walletAddress));
};

Create a client with a private key

You can create a client with a private key using a compatible client library.

import { Client } from "@xmtp/xmtp-js";
 
const privateKey = "your_private_key";
 
//ethers
import { Wallet } from "ethers";
const signer = new Wallet();
 
//viem
import { privateKeyToAccount } from "viem/accounts";
const hexPrivateKey = `0x${privateKey}`;
let account = privateKeyToAccount(privateKey);
let signer = createWalletClient({
  account,
  chain: mainnet,
  transport: http(),
});
 
// Create the client with a `Signer` from your application
const xmtp = await Client.create(signer, { env: "dev" });

Configure the client

Configure a client's network connection and other options using these client creation parameters:

Set the env client option to dev while developing. Set it to production before you launch.

XMTP network environments

An XMTP identity on the dev network is completely distinct from its XMTP identity on the production network, as are the messages associated with these identities.

• production: Use this network for production messages.

  • To send and receive messages on the production network, you can use the open source Converse web app connected to the production network: https://app.converse.xyz.

• dev: Use this network for development.

  • To send and receive messages on the dev network, you can use the open source Converse web app connected to the dev network: https://app-preview.converse.xyz.

• local: Use this network to have a client communicate with an XMTP node you are running locally. For example, an XMTP node developer can set env to local to generate client traffic to test a node running locally.