Skip to content
XMTP.org

FAQ about XMTP

Get answers to the most frequently asked questions about XMTP.

What works with XMTP?

In the spirit of web3 composability, here are just a few of the building blocks that work well with XMTP. Building your app with these tools can help you deliver and distribute an app—faster and with quality.

Wallet connectors

Here are some options for connecting wallets to your app built with XMTP:

Message payload storage

Here are some options for storing encrypted message payload content:

Decentralized social

Here are some decentralized social protocols that work with XMTP:

Wallet apps

XMTP can be used with EVM-compatible wallet apps that support ECDSA signing on the secp256k1 elliptic curve. These include common wallet apps such as:

The XMTP SDK does not include a wallet app abstraction, as XMTP assumes that developers have a way to obtain a wallet app connection.

Chains

XMTP works with externally owned accounts (EOAs) on Ethereum and Ethereum side-chains and L2s.

Because all Ethereum Virtual Machine (EVM) chains share the same Ethereum wallet and address format and XMTP messages are stored off-chain, XMTP is interoperable across EVM chains, including testnets. (XMTP itself does not use EVMs.)

For example, whether a user has their wallet app connected to Ethereum or an Ethereum side-chain or L2, their private key can generate and retrieve their XMTP key pair to give them access to XMTP.

XMTP is also chain-agnostic, so multi-chain support is possible.

Here are just a few chains that work with XMTP:

Smart contract wallets

To learn more about XMTP support for smart contract wallets, see this XIP in Draft status: XIP-44: Smart Contract Wallet Support.

Build with XMTP

Which languages and environments does the XMTP SDK support?

XMTP SDKs are available for multiple languages.

Which web3 libraries does the XMTP SDK require?

The XMTP SDK currently requires you to use ethers or another web3 library capable of supplying an ethers Signer, such as wagmi.

Is XMTP compatible with viem?

Yes, though not by default. To make them compatible, you must create a wrapper around viem. For example, see this Hey implementation.

import { ZERO_ADDRESS } from "@lenster/data/constants";
import { CHAIN_ID } from "src/constants";
import type { Address } from "viem";
import { useWalletClient } from "wagmi";
 
const useEthersWalletClient = (): {
  data: {
    getAddress: () => Promise<Address>;
    signMessage: (message: string) => Promise<string>;
  };
  isLoading: boolean;
} => {
  const { data, isLoading } = useWalletClient({ chainId: CHAIN_ID });
 
  const ethersWalletClient = {
    getAddress: async (): Promise<Address> => {
      return (await data?.account.address) ?? ZERO_ADDRESS;
    },
    signMessage: async (message: string): Promise<string> => {
      const signature = await data?.signMessage({ message });
      return signature ?? null; //lenster uses empty string which could be risky
    },
  };
 
  // eslint-disable-next-line @typescript-eslint/no-unused-vars
  const { signMessage, ...rest } = data ?? {};
 
  const mergedWalletClient = {
    data: {
      ...ethersWalletClient,
      ...{ ...rest },
    },
  };
 
  return { data: mergedWalletClient.data, isLoading };
};
 
export default useEthersWalletClient;

You can then call viem as shown in this Hey implementation.

const { data: walletClient, isLoading } = useEthersWalletClient();

Does XMTP work with Bun?

Currently, Bun does not offer full compatibility with XMTP. Use Yarn as an alternative to prevent any issues.

Using config files

React Scripts 5

  • CRACO: (Create React App Configuration Override) is a community solution for adding custom configurations to Create React App. It allows you to customize your configuration without ejecting from the default setup provided by Create React App.

    Install react-app-rewired:

    npm install craco

    Create the craco.config.js in your root directory:

    const webpack = require("webpack");
module.exports = {
  webpack: {
    plugins: [
      new webpack.ProvidePlugin({
        Buffer: ["buffer", "Buffer"],
      }),
    ],
    resolve: {
      fallback: {
        buffer: require.resolve("buffer/"),
      },
    },
  },
};

  • React-App-Rewired: react-app-rewired is a tool to tweak the Create React App (CRA) configuration without ejecting, similar to CRACO. Here's how you can use it:

    Install react-app-rewired:

    npm install react-app-rewired

    Modify the scripts in your package.json: Replace react-scripts with react-app-rewired. For example:

    "scripts": {
  "start": "react-app-rewired start",
  "build": "react-app-rewired build",
  "test": "react-app-rewired test",
  "eject": "react-app-rewired eject"
}

    Create a config-overrides.js file: In the root of your project, create a config-overrides.js file. This file will be used to modify the webpack config.

    const webpack = require("webpack");
 
module.exports = function override(config, env) {
  config.resolve.fallback = {
    ...config.resolve.fallback,
    buffer: require.resolve("buffer/"),
  };
  config.plugins = (config.plugins || []).concat([
    new webpack.ProvidePlugin({
      Buffer: ["buffer", "Buffer"],
    }),
  ]);
  return config;
};

  • Eject Method: Ejecting from CRA gives you full control over the configuration, but it's a one-way operation. Once you eject, you can't go back to the abstracted CRA setup.

    Eject the application:

    npm run eject

    Modify the Webpack Configuration: After ejecting, you'll have access to the config folder. Modify the webpack.config.js file:

    const webpack = require("webpack");
 
// Inside the module.exports object
module.exports = {
  // ... other configurations
 
  resolve: {
    // ... other resolve options
    fallback: {
      // ... other fallback options
      buffer: require.resolve("buffer/"),
    },
  },
  plugins: [
    // ... other plugins
    new webpack.ProvidePlugin({
      Buffer: ["buffer", "Buffer"],
    }),
  ],
};
WEBPACK
  • Webpack: vue.config.js or webpack.config.js:
const webpack = require("webpack");
 
module.exports = {
  configureWebpack: {
    plugins: [
      new webpack.ProvidePlugin({
        Buffer: ["buffer", "Buffer"],
      }),
    ],
  },
  transpileDependencies: true,
};
VITE
  • Vite: vite.config.js:
import { defineConfig } from "vite";
import { Buffer } from "buffer";
 
export default defineConfig({
  /**/
  define: {
    global: {
      Buffer: Buffer,
    },
  },
  /**/
});
NuxtJS
  • NuxtJS: nuxt.config.js:
export default {
  build: {
    extend(config, { isClient }) {
      if (isClient) {
        config.node = {
          Buffer: true,
        };
      }
    },
  },
};

Where can I get official XMTP brand assets?

See the XMTP brand guidelines GitHub repo.

How should I handle the XMTP onboarding flow in my app?

In your app onboarding flow, enable your users to activate XMTP DMs. User access to DMs can help with app engagement and re-engagement.

For example, here is a prompt to activate XMTP DMs in the onboarding flow to claim a Lens handle:

activatedmsscreen-width-500px

In your app onboarding flow, request user permission to display app-specific push notifications to reach users outside of an app session.

Network

Is the XMTP network decentralized?

Currently, Ephemera (the company) operates all of the network nodes in the two available XMTP network environments: dev and production.

These network nodes operate in US jurisdiction in compliance with Office of Foreign Assets Control (OFAC) sanctions and Committee on Foreign Investment in the United States (CFIUS) export compliance regulations. Accordingly, IP-based geoblocking is in place for the following countries/territories:

  • Cuba
  • Iran
  • North Korea
  • Syria
  • The Crimea, Donetsk People’s Republic, and Luhansk People’s Republic regions of Ukraine

To explore the software for the nodes that currently form the XMTP network, see the xmtp-node-go repo.

Ephemera is working toward a phased decentralization of the network.

Decentralization of the XMTP network will be achieved by a diverse set of independent third parties operating nodes all over the world. Decentralization is a top priority and is required to ensure that XMTP is able to serve everyone on the planet.

Is XMTP a blockchain?

XMTP is not a blockchain. Nodes on the XMTP network run software to store and transfer messages between blockchain accounts. For secure and reliable delivery of messages, the nodes participate in a consensus mechanism.

Ephemera is researching various consensus protocols that would allow the network to operate in a decentralized fashion while maintaining its current emphasis on user privacy and low-latency message delivery.

Will I be able to run my own XMTP node?

Yes, you will be able to run a node.

Ephemera is working toward a phased decentralization of the network.

Does XMTP have a token?

XMTP does not currently have a token. Disregard any information regarding airdrops or token sales. If and when an official token is introduced, announcements will be made exclusively through XMTP's official channels.

What is the relationship between Waku and XMTP?

XMTP currently uses the Waku protocol to relay messages between network nodes.

Waku is an unopinionated transport layer built around the libp2p publish/subscribe model. Waku is intentionally open-ended when it comes to handling options like message encoding and encryption, which content topics to use, and how to create and manage encryption keys linked to blockchain account addresses.

XMTP provides a standardized approach to addressing these options, focusing on maximizing compatibility across apps and ensuring message security and deliverability, while also enabling as many developers as possible to use XMTP to build interoperable messaging apps.

How do XMTP clients communicate with XMTP nodes?

Clients communicate with XMTP nodes through a gRPC (or JSON/HTTP) message API.

What is the expected network latency for message delivery and retrieval?

XMTP provides perceptibly real-time message delivery and retrieval. The network does not provide service level guarantees.

Is there a way to get a list of all current XMTP-enabled wallets?

XMTP doesn't provide a direct method to fetch all XMTP-enabled wallet addresses in bulk. You might consider using a third-party service to do so instead of building the functionality yourself.

For example, services like Blaze have compiled extensive lists of XMTP addresses by querying the XMTP canMessage API over time at a rate that avoids hitting the limits.

Does XMTP support group chat?

Yes. XMTP V3 supports group chat in React Native, Android, iOS, and Node.js SDKs.

Fees

Who pays to keep the network running?

Ephemera is committed to keeping the network running. Future incentive mechanisms will enable the network to run autonomously of Ephemera.

Will XMTP charge messaging fees?

Currently, messaging incurs no fee. As XMTP decentralizes, messaging between participants that opt-in will remain free, while unsolicited messages may incur fees or see token staking requirements.

There are no messaging-related fees incurred by developers for building with the XMTP SDK.

What are the costs of XMTP message storage and retrieval?

Messages are stored off-chain on the XMTP network, with all nodes currently hosted by Ephemera. Ephemera currently absorbs all message storage and retrieval costs.

There are no message storage and retrieval-related fees incurred by developers for building with the XMTP SDK.

Security

Has XMTP undergone a security audit?

The XMTP JavaScript SDK (xmtp-js) was verified by CertiK on Feb 6, 2023. Read their XMTP security assessment.

How does XMTP establish a secure and fraud-proof relationship between two identities?

Blockchain accounts sign and advertise a set of keys to start using XMTP. XMTP uses these keys to establish a shared secret between the blockchain accounts. It then uses the shared secret to generate a key used to encrypt an invitation that allows the blockchain accounts to start exchanging messages. No third-party apps or relayers are involved in this process.

To learn more about these keys, see Key generation and usage in XMTP.

To learn more about invitation and message encryption, see Invitation and message encryption with XMTP.

Does each blockchain account address have a corresponding XMTP identity?

Yes. Each blockchain account address is represented by an XMTP identity key. This identity key is a part of a key bundle that only the address that generated it can use to authenticate messages.

To learn more about XMTP identity keys, see Key generation and usage in XMTP.

Why do apps built with XMTP require a user to sign with their blockchain account private keys each time they start a new messaging session?

When a user starts a new messaging session, they must sign with their blockchain account private key to decrypt their XMTP key bundle. The key bundle is then used for invitation and message decryption.

Because there is no secure place in the browser to persist a decrypted key bundle, the app can use the bundle for the current session only. Once the user starts a new session, such as after refreshing their browser, they must sign again to decrypt their key bundle.

If you are using the JavaScript client SDK, you might consider manually handling private key storage, but only with the understanding that this approach requires the utmost care.

Based on developer and community feedback, we are researching more robust approaches to secure key management.

To learn more about these keys, see Key generation and usage in XMTP.

Storage

Where are XMTP messages stored?

XMTP stores messages in the XMTP network before and after retrieval. Application-specific message storage policies may vary.

What are the XMTP message retention policies?

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

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 and XMTP Announcements forum.

Different approaches to long-term message storage are currently being researched.

Messages

Which message formats and metadata does XMTP support?

XMTP transports a message payload as a set of bytes that can represent any format that a developer wants to support, such as plain text, JSON, or even non-text binary or media content.

With XMTP, these message formats are called content types. Currently, there are two basic content types available. These content types aim to establish broad compatibility among apps built with XMTP.

The XMTP community can propose and adopt standards for other content types, either informally or through a governance process.

Message payloads also include references to timestamps. However, timestamps are not currently independently verified and can be set to any value by the sending app.

To learn more about content types, see Content types.

To learn more about the XMTP improvement proposals governance process, see What is an XIP?

Have other questions or ideas about message formats and metadata? Post to the XMTP Community Forums.

Does XMTP have a maximum message size?

Yes. Messages sent on the XMTP network are limited to just short of 1MB (1048214 bytes).

For this reason, XMTP supports message attachments.

Does XMTP support message attachments?

Yes. See Support attachments in your app built with XMTP.

Does XMTP support deleting and editing messages?

Not currently. However, Ephemera is exploring ways to support message deletion and editing.

Message patterns

Is XMTP more like email or chat?

XMTP enables developers to implement messaging features and UX paradigms that best fit their needs. As a result, messages sent using apps built with XMTP might resemble many typical forms of communication, such as email, chat, text messaging, push notifications, and more.

Does XMTP support real-time conversations?

Real-time chat is a core use case for XMTP and is demonstrated by the XMTP Inbox chat app.

To learn more about how the XMTP Inbox chat app is built, see the xmtp-inbox-web repo.

Does XMTP support broadcast messaging?

Yes. See Broadcast messages with XMTP.

Ephemera

What is Ephemera?

Ephemera is a web3 software company that contributes to XMTP, an open network, protocol, and standards for secure messaging between blockchain accounts.

Ephemera employees work alongside other XMTP community members to build with and extend XMTP. Community contributions and participation are critical to the development and adoption of XMTP.

Does Ephemera plan to build apps or are you focused 100% on the protocol?

Ephemera focuses on serving developers. We build SDKs, developer tools, and example apps that help developers build great experiences with XMTP.