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Quickstart for the XMTP JavaScript SDK

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The XMTP JavaScript SDK (xmtp-js) provides a TypeScript implementation of an XMTP client for use with JavaScript and React applications.

Build with xmtp-js to provide messaging between blockchain wallet addresses, delivering on use cases such as wallet-to-wallet messaging and dapp-to-wallet notifications.

For a demonstration of the core concepts and capabilities of the xmtp-js client SDK, see the example React app repo.

xmtp-js has not undergone a formal security audit.

To learn more about XMTP and get answers to frequently asked questions, see FAQ about XMTP.

Breaking revisions

Because xmtp-js is in active development, you should expect breaking revisions that might require you to adopt the latest SDK release to enable your app to continue working as expected.

XMTP communicates about breaking revisions in the XMTP Discord community, providing as much advance notice as possible. Additionally, breaking revisions in an xmtp-js release are described on the Releases page.

Deprecation schedule

Older versions of the SDK will eventually be deprecated, which means:

  1. The network will not support and will eventually actively reject connections from clients using deprecated versions.
  2. Bugs will not be fixed in deprecated versions.

The following table provides the deprecation schedule:

Announced  Effective                    Minimum versionRationale
2022-08-182022-11-08v6.0.0The XMTP network will stop supporting the Waku/libp2p-based client interface in favor of the new GRPC-based interface.

Issues and PRs are welcome in accordance with XMTP contribution guidelines.

XMTP production and dev network environments

XMTP provides both production and dev network environments to support the development phases of your project.

The production and dev networks are completely separate and not interchangeable. For example, for a given blockchain account address, its XMTP identity on dev network is completely distinct from its XMTP identity on the production network, as are the messages associated with these identities. In addition, XMTP identities and messages created on the dev network can't be accessed from or moved to the production network, and vice versa.

info

When you create a client, it connects to the XMTP dev environment by default. To learn how to use the env parameter to set your client's network environment, see Configuring the Client.

The env parameter accepts one of three valid values: dev, production, or local. Here are some best practices for when to use each environment:

  • dev: Use to have a client communicate with the dev network. As a best practice, set env to dev while developing and testing your app. Follow this best practice to isolate test messages to dev inboxes.

  • production: Use to have a client communicate with the production network. As a best practice, set env to production when your app is serving real users. Follow this best practice to isolate messages between real-world users to production inboxes.

  • local: Use 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.

The production network is configured to store messages indefinitely. XMTP may occasionally delete messages and keys from the dev network, and will provide advance notice in the XMTP Discord community.

Installation

npm install @xmtp/xmtp-js

Additional configuration is required in React environments due to the removal of polyfills from Webpack 5.

Create React App

Use react-scripts prior to version 5.0.0. For example:

npx create-react-app my-app --scripts-version 4.0.2

Or downgrade after creating your app.

Next.js

In next.config.js:

webpack: (config, { isServer }) => {
if (!isServer) {
config.resolve.fallback.fs = false
}
return config
}

Usage

The API revolves around a network Client that allows retrieving and sending messages to other network participants. A Client must be connected to a wallet on startup. If this is the very first time the Client is created, the client will generate a key bundle that is used to encrypt and authenticate messages. The key bundle persists encrypted in the network using a wallet signature. The public side of the key bundle is also regularly advertised on the network to allow parties to establish shared encryption keys. All this happens transparently, without requiring any additional code.

import { Client } from '@xmtp/xmtp-js'
import { Wallet } from 'ethers'

// You'll want to replace this with a wallet from your application
const wallet = Wallet.createRandom()
// Create the client with your wallet. This will connect to the XMTP development network by default
const xmtp = await Client.create(wallet)
// Start a conversation with XMTP
const conversation = await xmtp.conversations.newConversation(
'0x3F11b27F323b62B159D2642964fa27C46C841897'
)
// Load all messages in the conversation
const messages = await conversation.messages()
// Send a message
await conversation.send('gm')
// Listen for new messages in the conversation
for await (const message of await conversation.streamMessages()) {
console.log(`[${message.senderAddress}]: ${message.content}`)
}

Creating a Client

A Client is created with Client.create(wallet: ethers.Signer): Promise<Client> that requires passing in a connected Wallet. The Client will request a wallet signature in 2 cases:

  1. To sign the newly generated key bundle. This happens only the very first time when key bundle is not found in storage.
  2. To sign a random salt used to encrypt the key bundle in storage. This happens every time the Client is started (including the very first time).
info

The Client connects to the XMTP dev environment by default. Use ClientOptions to change this and other parameters of the network connection.

import { Client } from '@xmtp/xmtp-js'
// Create the client with an `ethers.Signer` from your application
const xmtp = await Client.create(wallet)

Configuring the Client

The client's network connection and key storage method can be configured with these optional parameters of Client.create:

ParameterDefaultDescription
envdevConnect to the specified XMTP network environment. Valid values also include dev, production, or local. For important details about working with these environments, see XMTP production and dev network environments.
apiUrlUndefinedManually specify an API URL to use. If specified, value of env will be ignored.
keyStoreTypenetworkTopicStoreV1Persist the wallet's key bundle to the network, or use static to provide private keys manually.
codecs[TextCodec]Add codecs to support additional content types.
maxContentSize100MMaximum message content size in bytes.
appVersionUndefinedAdd a client app version identifier that's included with API requests. For example, you can use the following format: appVersion: APP_NAME + '/' + APP_VERSION. Setting this value provides telemetry that shows which apps are using the XMTP client SDK. This information can help XMTP developers provide app support, especially around communicating important SDK updates, including deprecations and required upgrades.

Conversations

Most of the time, when interacting with the network, you'll want to do it through conversations. Conversations are between two wallets.

import { Client } from '@xmtp/xmtp-js'
// Create the client with an `ethers.Signer` from your application
const xmtp = await Client.create(wallet)
const conversations = xmtp.conversations

List existing conversations

You can get a list of all conversations that have had 1 or more messages exchanged in the last 30 days.

const allConversations = await xmtp.conversations.list()
// Say gm to everyone you've been chatting with
for (const conversation of allConversations) {
console.log(`Saying GM to ${conversation.peerAddress}`)
await conversation.send('gm')
}

Listen for new conversations

You can also listen for new conversations being started in real-time. This will allow applications to display incoming messages from new contacts.

Warning: this stream will continue infinitely. To end the stream you can either break from the loop, or call await stream.return()

const stream = await xmtp.conversations.stream()
for await (const conversation of stream) {
console.log(`New conversation started with ${conversation.peerAddress}`)
// Say hello to your new friend
await conversation.send('Hi there!')
// Break from the loop to stop listening
break
}

Start a new conversation

You can create a new conversation with any Ethereum address on the XMTP network.

const newConversation = await xmtp.conversations.newConversation(
'0x3F11b27F323b62B159D2642964fa27C46C841897'
)

Sending messages

To be able to send a message, the recipient must have already started their Client at least once and consequently advertised their key bundle on the network. Messages are addressed using wallet addresses. The message payload can be a plain string, but other types of content can be supported through the use of SendOptions (see Different types of content for more details)

const conversation = await xmtp.conversations.newConversation(
'0x3F11b27F323b62B159D2642964fa27C46C841897'
)
await conversation.send('Hello world')

List messages in a conversation

You can receive the complete message history in a conversation by calling conversation.messages()

for (const conversation of await xmtp.conversations.list()) {
// All parameters are optional and can be omitted
const opts = {
// Only show messages from last 24 hours
startTime: new Date(new Date().setDate(new Date().getDate() - 1)),
endTime: new Date(),
}
const messagesInConversation = await conversation.messages(opts)
}

List messages in a conversation with pagination

It may be helpful to retrieve and process the messages in a conversation page by page. You can do this by calling conversation.messagesPaginated() which will return an AsyncGenerator yielding one page of results at a time. conversation.messages() uses this under the hood internally to gather all messages.

const conversation = await xmtp.conversations.newConversation(
'0x3F11b27F323b62B159D2642964fa27C46C841897'
)

for await (const page of conversation.messagesPaginated({ pageSize: 25 })) {
for (const msg of page) {
// Breaking from the outer loop will stop the client from requesting any further pages
if (msg.content === 'gm') {
return
}
console.log(msg.content)
}
}

Listen for new messages in a conversation

You can listen for any new messages (incoming or outgoing) in a conversation by calling conversation.streamMessages().

A successfully received message (that makes it through the decoding and decryption without throwing) can be trusted to be authentic, i.e. that it was sent by the owner of the message.senderAddress wallet and that it wasn't modified in transit. The message.sent timestamp can be trusted to have been set by the sender.

The Stream returned by the stream methods is an asynchronous iterator and as such usable by a for-await-of loop. Note however that it is by its nature infinite, so any looping construct used with it will not terminate, unless the termination is explicitly initiated (by breaking the loop or by an external call to Stream.return())

const conversation = await xmtp.conversations.newConversation(
'0x3F11b27F323b62B159D2642964fa27C46C841897'
)
for await (const message of await conversation.streamMessages()) {
if (message.senderAddress === xmtp.address) {
// This message was sent from me
continue
}
console.log(`New message from ${message.senderAddress}: ${message.content}`)
}

Checking if an address is on the network

If you would like to check and see if a blockchain address is registered on the network before instantiating a client instance, you can use Client.canMessage.

import { Client } from '@xmtp/xmtp-js'

const isOnDevNetwork = await Client.canMessage(
'0x3F11b27F323b62B159D2642964fa27C46C841897'
)
const isOnProdNetwork = await Client.canMessage(
'0x3F11b27F323b62B159D2642964fa27C46C841897',
{ env: 'production' }
)

Handling multiple conversations with the same blockchain address

With XMTP, you can have multiple ongoing conversations with the same blockchain address. For example, you might want to have a conversation scoped to your particular application, or even a conversation scoped to a particular item in your application.

To accomplish this, just set the conversationId when you are creating a conversation. We recommend conversation IDs start with a domain, to help avoid unwanted collisions between your application and other apps on the XMTP network.

// Start a scoped conversation with ID mydomain.xyz/foo
const conversation1 = await xmtp.conversations.newConversation(
'0x3F11b27F323b62B159D2642964fa27C46C841897',
{
conversationId: 'mydomain.xyz/foo',
}
)

// Start a scoped conversation with ID mydomain.xyz/bar. And add some metadata
const conversation2 = await xmtp.conversations.newConversation(
'0x3F11b27F323b62B159D2642964fa27C46C841897',
{
conversationId: 'mydomain.xyz/bar',
metadata: {
title: 'Bar conversation',
},
}
)

// Get all the conversations
const conversations = await xmtp.conversations.list()
// Filter for the ones from your application
const myAppConversations = conversations.filter(
(convo) =>
convo.context?.conversationId &&
convo.context.conversationId.startsWith('mydomain.xyz/')
)

for (const conversation of myAppConversations) {
const conversationId = conversation.context?.conversationId
if (conversationId === 'mydomain.xyz/foo') {
await conversation.send('foo')
}
if (conversationId === 'mydomain.xyz/bar') {
await conversation.send('bar')
console.log(conversation.context?.metadata.title)
}
}

Different types of content

All the send functions support SendOptions as an optional parameter. The contentType option allows specifying different types of content than the default simple string, which is identified with content type identifier ContentTypeText. Support for other types of content can be added by registering additional ContentCodecs with the Client. Every codec is associated with a content type identifier, ContentTypeId, which is used to signal to the Client which codec should be used to process the content that is being sent or received. See XIP-5 for more details on codecs and content types.

Codecs and content types may be proposed as interoperable standards through XRCs. If there is a concern that the recipient may not be able to handle a non-standard content type, the sender can use the contentFallback option to provide a string that describes the content being sent. If the recipient fails to decode the original content, the fallback will replace it and can be used to inform the recipient what the original content was.

// Assuming we've loaded a fictional NumberCodec that can be used to encode numbers,
// and is identified with ContentTypeNumber, we can use it as follows.

xmtp.registerCodec:(new NumberCodec())
conversation.send(3.14, {
contentType: ContentTypeNumber,
contentFallback: 'sending you a pie'
})

Additional codecs can be configured through the ClientOptions parameter of Client.create. The codecs option is a list of codec instances that should be added to the default set of codecs (currently only the TextCodec). If a codec is added for a content type that is already in the default set, it will replace the original codec.

// Adding support for `xmtp.org/composite` content type
import { CompositeCodec } from '@xmtp/xmtp-js'
const xmtp = Client.create(wallet, { codecs: [new CompositeCodec()] })

Compression

Message content can be optionally compressed using the compression option. The value of the option is the name of the compression algorithm to use. Currently supported are gzip and deflate. Compression is applied to the bytes produced by the content codec.

Content will be decompressed transparently on the receiving end. Note that Client enforces maximum content size. The default limit can be overridden through the ClientOptions. Consequently a message that would expand beyond that limit on the receiving end will fail to decode.

conversation.send('#'.repeat(1000), {
compression: 'deflate',
})

Manually handling private key storage

The SDK will handle key storage for the user by encrypting the private key bundle using a signature generated from the wallet, and storing the encrypted payload on the XMTP network. This can be awkward for some server-side applications, where you may only want to give the application access to the XMTP keys but not your wallet keys. Mobile applications may also want to store keys in a secure enclave rather than rely on decrypting the remote keys on the network each time the application starts up.

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

import { Client } from '@xmtp/xmtp-js'
// Get the keys using a valid ethers.Signer. Save them somewhere secure.
const keys = await Client.getKeys(wallet)
// Create a client using keys returned from getKeys
const client = await Client.create(null, { privateKeyOverride: keys })

The keys returned by getKeys should be treated with the utmost care as compromise of these keys will allow an attacker to impersonate the user on the XMTP network. Ensure these keys are stored somewhere secure and encrypted.

Under the hood

Using xmtp.conversations hides the details of this, but for the curious this is how sending a message on XMTP works. The first message and first response between two parties is sent to three separate Waku content topics:

  1. Sender's introduction topic
  2. Recipient's introduction topic
  3. Conversation topic shared by the sender and the recipient

This is used to establish a shared secret and negotiate a topic to communicate on. Any following messages are sent to the conversation topic only.

The introduction topics allow the participants to reconstruct the list of conversations that they participate(d) in.

The conversation topics carry the contents of the conversations.