Introduction to XMTP

XMTP (Extensible Message Transport Protocol) is an open protocol, network, and standards for secure, private web3 messaging.

XMTP's extensible design enables a diverse set of use cases for sending message data between web3 identities. For example, building with the XMTP client SDK, developers can enhance their apps with:

• User-to-user direct messages
• App-to-user notifications
• Creator-to-community announcements

Because the XMTP network persists messages, and those messages are tied to web3 identities as opposed to a specific client app, each web3 identity has a portable inbox of that it can access using any client app built with XMTP.

Developers can also build tools for decentralized apps (dapps), decentralized autonomous organizations (DAOs), creators, and protocols to re-engage users with web3 messaging.

XMTP has been implemented to work with Ethereum Virtual Machine (EVM)-compatible wallet apps and blockchain accounts (wallets), though XMTP itself does not use EVMs. XMTP also works with other web3 identities that apps built with XMTP can derive from Ethereum accounts, such as ENS names and Lens profiles.

To learn more, see Wallet apps and blockchains supported by XMTP.

Blockchain account versus wallet app

In web3, people commonly use wallet as shorthand to refer to a blockchain account, crypto account, or wallet address. This documentation uses blockchain account to refer to this concept of a unique identifier for a blockchain wallet held by a user. This documentation uses wallet app to refer to a tool for managing blockchain accounts.

XMTP’s primary contributor, XMTP Labs, is funded by some of the industry’s top venture capital funds, including a16z Crypto and Coinbase Ventures.

XMTP at a glance

Here are some key considerations as you explore building with XMTP for secure web3 messaging:

Consideration	Description
Message direction	Bidirectional
Participant identities	Any EVM blockchain EOA (externally owned account) can send a message to any other EVM blockchain EOA that has advertised its XMTP identity on the network.
Chain focus	Chain-agnostic, but currently requires an EVM blockchain account.
Wallet app compatibility	EVM-compatible wallets capable of signing with private keys, such as MetaMask, Coinbase Wallet, and Rainbow Wallet.
Authentication	An XMTP-specific key bundle derived from a wallet address signature is used to authenticate participant identities. To learn more about authentication, see Participant authentication and message encryption.
Message encryption	AES-256-GCM and modified Diffie-Hellman key agreement. Messages are encrypted individually by default and are readable by message participants only. To learn more about message encryption, see Participant authentication and message encryption.
Message delivery	Messages are immediately relayed by XMTP nodes, using the Waku protocol.
Message storage	Messages are stored off-chain in the XMTP network, with all nodes currently hosted by XMTP Labs. We will publish a phased decentralization roadmap in Fall 2022.
Supported content types	Plaintext messages as a standard content type, but custom content types are supported as well. To learn more, see Content types.
Adoption of standard content types	Open, extensible, and community-governed via XIP-5 (XMTP Improvement Proposal-5). To learn more, see XIP-5 Message Content Types.
Implementation	Any app built with the XMTP client SDK can send or receive messages. To learn more, see Client SDK.
Receiving messages	Any frontend built with the XMTP client SDK can receive messages. To learn more, see Client SDK.
Environments	JavaScript. Swift and React Native are on the roadmap.
Message cost	Most messaging incurs no fee. As XMTP decentralizes, messaging between participants that opt-in will remain free, while unsolicited messages will often incur fees or see token staking requirements.
Decentralization	XMTP network nodes are run by XMTP Labs at this time. In the future, network node software will be open sourced and anyone will be welcome to operate a node. Client implementation is permissionless, nor is permission required to access and develop with the SDK. Permission isn't required to connect to the XMTP network to send/receive messages on behalf of users. We will publish a phased decentralization roadmap in Fall 2022.

Protocol overview

A user can send and receive encrypted XMTP messages using an app with an embedded XMTP client, authenticating using a wallet signature. XMTP network nodes persist the user's messages

Clients and nodes are implemented as Waku2 peers but with XMTP-specific functions and capabilities.

Clients

XMTP clients have the following responsibilities:

• Encode and decode message formats using a standard interface
• Encrypt and decrypt encoded message content
• Submit and retrieve encrypted messages to and from the XMTP Network
• Generate secure wallet-based identities capable of encrypting and decrypting messages
• Persist wallet-based identities locally or on the XMTP Network

Nodes

XMTP nodes have the following responsibilities:

• Relay encrypted messages into replicated storage
• Retrieve encrypted messages from storage and deliver them to clients
• Persist and advertise wallet-based identities

XMTP client SDK

The XMTP JavaScript SDK is a TypeScript implementation of an XMTP client for use with JavaScript and React apps.

Explore the XMTP JavaScript SDK on GitHub.

Have questions? Get help from the XMTP Discord community.

To learn more about how you can contribute to XMTP, see Contribute.

Example apps

• Explore the example-chat-react repo on GitHub. This example React app demonstrates the core capabilities of the XMTP JavaScript SDK. You can customize and deploy the app if you want to.
• XMTP Labs hosts deployments of the example-chat-react app to provide people with a way to try out a basic app built with XMTP.
  • Try the app connected to the XMTP production network
  • Try the app connected to the XMTP dev network