Skip to content

Secure Low-Latency Interactive Messaging

part of

What is SLIM?

Secure Low-Latency Interactive Messaging (SLIM) is the secure transport layer for agent communication, an open source project under the Linux Foundation building the Internet of Agents. While protocols like A2A define what agents say, SLIM defines how those messages are securely delivered across distributed networks—whether agents run in a data center, in a browser, on mobile devices, or across organizational boundaries.

SLIM combines gRPC's performance over HTTP/2, native channel and group messaging, end-to-end encryption with the Message Layer Security (MLS) protocol, native RPC support (SLIMRPC), and a clean separation of control and data planes for scalability—serving as the transport for A2A, MCP, and custom agent protocols.

Why use SLIM

  • Transport for Agent Protocols

    Carry A2A, MCP, SLIMRPC, and custom agent protocols over a single secure overlay instead of bespoke per-protocol networking.

  • End-to-End Encryption

    Message Layer Security (MLS) keeps payloads encrypted from source to destination, even when traffic traverses shared routing infrastructure.

  • Network-Topology Independence

    Agents connect outbound to SLIM nodes and are reachable by hierarchical name—no inbound ports, VPNs, or NAT traversal required.

Get started with SLIM

  • Get Started

    Run a SLIM node and send your first messages in minutes.

    Getting Started

  • Read the Introduction

    Understand core concepts, the messaging layer, and the controller.

    Overview

  • Dive into the Specification

    Explore the SLIM Internet Draft and protocol definition.

    SLIM Specification

  • Integrations

    Run A2A, MCP, SLIMRPC, and OpenTelemetry over SLIM.

    Integrations

  • Configure

    Tune the data plane for your environment.

    Configuration Reference

  • Reference

    Controller API and configuration details.

    Controller Reference

  • Source Code

    Reference implementation and related repositories.

    github.com/agntcy/slim

  • Join the Community

    Connect with maintainers and contributors across the AGNTCY project.

    SLIM Community

  • Linux Foundation Press Release

    Read how the Linux Foundation welcomed the AGNTCY project to standardize open multi-agent system infrastructure and break down AI agent silos.

    LF press release