Agent-to-Agent Protocol

A2A Agents

The emerging directory of interoperable AI agents. Browse capabilities, authentication methods and frameworks for the A2A ecosystem.

A2A Reference Agent

A2A Project (Linux Foundation)

active

The reference implementation of the Agent2Agent protocol, demonstrating agent discovery via Agent Cards and task exchange.

Capabilities

task-delegationstreamingagent-card-discovery
custom bearer

CrewAI A2A Bridge

CrewAI

beta

A bridge that lets CrewAI crews participate in A2A agent networks as discoverable, callable services.

Capabilities

role-based-tasksdelegation
crewai api-key

Google ADK Agent

Google

active

Agents built with Google's Agent Development Kit, natively supporting A2A for cross-agent interoperability.

Capabilities

task-delegationstreamingtool-uselong-running-tasks
adk oauth

LangGraph A2A Server

LangChain

beta

Exposes LangGraph agents over the A2A protocol so they can be discovered and called by other agents.

Capabilities

multi-turn-tasksstreamingtool-use
langgraph api-key

Semantic Kernel A2A

Microsoft

beta

Semantic Kernel agents exposed over A2A, enabling enterprise .NET agents to interoperate across vendors.

Capabilities

plugin-tasksdelegationstreaming
semantic-kernel oauth