Cross-Consensus & Cross-Chain Messaging

Web3’s native tongue

For blockchains to work together and form the basis of Web3, they need a common language for communication. Polkadot sets the standard with XCM, a powerful format for secure messaging across Polkadot-native blockchains (called parachains) and with external networks via bridges.

Get ready for the era of interoperability

XCM is a language for building innovative new cross-chain applications and services. Giving applications the ability to span multiple blockchains allows them to leverage the key features and strengths of each for new interoperable use cases.

XCM unlocks:

Arbitrary message passing

Cross-chain token & NFT transfers

Reserve-backed assets

Multichain smart contracts, dapps, & DeFi

Batched transactions

Multichain DAOs & Treasuries

Paying fees between chains and in any native token

Bringing external tokens into Polkadot

On-chain scheduling

Off-chain computation, data, & oracles

Cross-chain certification & attestation

Cross-chain reputation systems

Mitigating MEV and arbitrage bots

NFT staking

Hoon Kim

CTO @ Astar

This is huge - the possibilities are endless! When we have XCM, we have a stable and reliable interchain messaging channel that is far superior to the fragmented bridges. I can imagine a future where more and more projects use XCM to create something that was impossible just a couple of years ago.

450+
Projects

Giving voice to a growing ecosystem

Polkadot has one of the most active developer communities in blockchain. XCM connects a growing ecosystem of 450+ projects building the next generation of blockchain apps and services and pioneering the world of Web3.

Infrastructure & Tooling
IoT & Robotics
Finance
Social Networking
Oracles
Privacy
Scaling
NFT
Wallets
Smart Contracts
Social Impact & Humanitarian
User Interface
Supply Chain & Logistics
Communications and Media
AI & Computing
Bridges
DeFi
Identity
Gaming and Metaverse
Data & Analytics
Retail & E-commerce
Energy
Healthcare
Government & Public Sector
Enterprise & Consortium
Distributed File Storage

Dominik Harz

CTO @ Interlay

XCM is the heart of the Polkadot ecosystem. For Interlay, it's the main reason we built on Polkadot: a way for us to seamlessly integrate with other applications out of the box, instead of spending months/years per custom bridge.

Changing the cross-chain game

XCM is the next great leap for cross-chain technology, offering several improvements over previous bridging solutions:

Supports rich data

Previous cross-chain technologies mostly involved moving tokens from one chain to another. XCM messages can contain any type of data, enabling not just cross-chain token transfers but feature-rich cross-chain applications. This will lead to innovative new services not possible on legacy networks.

Programmable

Much more than messages in the conventional sense, XCM messages are actually computer programs sent from one place and executed in another. This enables a level of cross-chain programmability never before seen in blockchain technology: with XCM, different blockchains can now program each other.

Secure & trustless

Before XCM, blockchains could only communicate via bridges that relied on trusted third parties, creating a ‘weakest link’ problem and leading to several infamous hacks. On Polkadot, messages between parachains share the same high security as the entire network, and do not require funds to be deposited with centralized and vulnerable third-party custodians.

Cross-consensus

XCM works not just between different blockchains but also between smart contracts on different virtual machines, between Substrate pallets, and over bridges. It can even connect networks built on different consensus mechanisms. For example, XCM could be used to communicate between a proof-of-work network like Bitcoin and a proof-of-stake network like Polkadot.

Lucas Vogelsang

CEO @ Centrifuge

XCM brings the true power of Polkadot to light and delivers on the vision of a scalable multichain future; the different parachains on Polkadot are now able to collaborate and assets can move around quickly without taking on any security risks that come from bridges.

How XCM works

XCM provides instructions for how to compose, send, and interpret cross-chain messages. Once received, the instructions contained in XCM messages are executed by the destination chain.

XCM messages contain instructions, assets, and any type of data:

Chain A

Chain B

XCM messages can be sent over various routes and channels:

Between parachains

Messages between parachains are sent via XCMP channels (currently live as XCMP-Lite aka HRMP)

Parachain - Relay Chain

Messages between the Relay Chain and a single parachain are sent via VMP channels

Over bridges

Messages between Polkadot and external blockchain networks, or between two solo chains outside the Polkadot network, are sent over bridges

Eliott Teissonniere

CTO @ Nodle

XCM will allow us to leverage the unique features from our parachain partners in the most secure manner possible, without having to reinvent the wheel. For instance, we will be able to run a DAO on Astar that manages funds on Acala and controls real-world devices via Nodle.

Unlocking the potential of asynchronous composability

On single isolated blockchains, messages are sent and executed synchronously (in a single instant). This works well for many things, but rules out functionality that requires freedom from time constraints, such as on-chain scheduling. Cross-chain XCM messages are asynchronous, allowing developers to trigger functions across several chains to take place variably over time.

Dive deeper and get started

Learn more about how XCM works in the Polkadot Wiki. Ready to start building? Get in touch for hands-on guidance and support.

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Secure communication for a multichain world.