XMTP protocol overview
XMTP is a decentralized messaging protocol that enables secure, end-to-end encrypted communication between blockchain addresses. This section covers the technical foundations and implementation details of how XMTP works under the hood.
Architecture fundamentals
With XMTP, messages are routed through topics, which are unique addresses that identify conversation channels. Messages are packaged as envelope types that contain the actual message data plus metadata for routing and processing.
The protocol prioritizes security through advanced cryptographic techniques, delivering end-to-end encryption for both 1:1 and group conversations. To learn more, see XMTP's security properties and how wallet signatures authenticate users.
Group messaging mechanics
For group conversations, XMTP introduces sophisticated state management:
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Epochs represent the cryptographic state of a group at any point in time. Each group operation (like adding members) creates a new epoch with fresh encryption keys. This concept comes from Messaging Layer Security, which XMTP builds upon.
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Intents provide reliable state management through an internal bookkeeping system that handles retries, crashes, and race conditions when applying group changes.
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Cursors enable efficient message synchronization by tracking where each client left off when fetching new messages.
Key concepts
| Concept | Purpose | Key benefit |
|---|---|---|
| Security | End-to-end encryption | Privacy and message integrity |
| Topics | Message routing and addressing | Efficient pub/sub architecture |
| Envelope types | Message format and structure | Standardized communication protocol |
| Epochs | Group cryptographic state | Key rotation and post-compromise security |
| Intents | Reliable group operations | Consistency despite network issues |
| Cursors | Message synchronization | Efficient incremental updates |
| Wallet signatures | Authentication | Verified sender identity |
Protocol evolution
XMTP evolves through XMTP Improvement Proposals (XIPs), which are design documents that propose new features and improvements. This governance process ensures systematic and decentralized protocol development.
Additional resources
For a broader vision of XMTP's approach to core concepts, see the following topics on xmtp.org:
Who should read these docs
The protocol documentation is designed for:
- Protocol contributors working on XMTP's core implementation
- Security researchers auditing XMTP's cryptographic design
- Anyone curious about the technical details behind XMTP's messaging
For most developers, the Build chat apps and Build agents sections provide the practical guidance needed to build with XMTP.