The Agent2Agent (A2A) Protocol is revolutionizing how AI agents communicate and collaborate - enabling seamless interoperability across different frameworks, vendors, and platforms. This repository collects the best resources to help developers build A2A-compatible agents.

Contents

🤔 What is A2A? (Briefly)

A2A (Agent2Agent) is an open protocol from Google and partners enabling different AI agents (from various vendors/frameworks) to communicate securely and collaborate on tasks. It aims to break down silos between isolated agent systems, allowing for more complex cross-application automation.

⭐ Official Website: a2aproject.github.io/A2A | ⭐ Official GitHub: github.com/a2aproject/A2A | 🌐 Multilingual Docs (EN/ZH/JA): agent2agent.ren

💡 Key Principles

  • Simple: Uses existing standards (HTTP, JSON-RPC, SSE).
  • Enterprise Ready: Focuses on Auth, Security, Privacy, Monitoring.
  • Async First: Handles long-running tasks & human-in-the-loop.
  • Modality Agnostic: Supports Text, Files, Forms, Streams, etc.
  • Opaque Execution: Agents interact without sharing internal logic/tools.

⚙️ How Does A2A Work? (High Level)

  1. Discovery: Agents publish an Agent Card (JSON) describing capabilities, endpoint, and auth needs.
  2. Communication: A Client agent sends a Task request (containing a Message with Parts) to a Remote Agent (Server) using HTTP/JSON-RPC 2.0.
  3. Execution & Response: The Server processes the task, updating its status. It responds with the final status and any generated Artifacts (results, also containing Parts).
  4. Updates: For long tasks, the Server can optionally stream TaskStatusUpdateEvent or TaskArtifactUpdateEvent via Server-Sent Events (SSE) or use Push Notifications.

For details, see the Official Technical Documentation.

🚀 Getting Started with A2A

New to A2A? Here's a suggested path:

  1. Understand the Basics: Read the sections above (What is A2A?, Key Principles, How it Works). Check the 📰 Announcement Blog Post.
  2. Explore Core Concepts: Dive into the 📖 Official Technical Documentation, focusing on Agent Card, Task, Message, Part, and Artifact.
  3. See it in Action: Watch the 🎥 Official Demo Video and explore the code for the 🌐 Multi-Agent Web App Demo.
  4. Run the Samples: Clone the Official Samples Repo and follow its instructions to run a client (like the CLI) and a sample agent (e.g., LangGraph or Genkit agent).
  5. Review the Code: Look at the common (Python) or server/client (JS/TS) libraries in the official samples to see how A2A communication is implemented.
  6. Try Building: Adapt a sample or use a library to create your own basic A2A agent or client.

🏛️ Official Resources

📜 Specification & Core Concepts

(See How Does A2A Work? above for summaries)

⚙️ Implementations & Libraries

Official Samples

These demonstrate basic A2A client/server communication.

Language Sample Name One-line Description GitHub URL
🔷 TypeScript Genkit SDK Core TS SDK + CLI, builds shared code for front- and backend https://github.com/a2aproject/a2a-samples/tree/main/samples/js
Movie Recommendation Agent Movie-recommendation conversational agent built with Genkit https://github.com/a2aproject/a2a-samples/tree/main/samples/js/src/agents/movie-agent
TypeScript Client Pure-frontend call example written in TS https://github.com/a2aproject/a2a-samples/tree/main/samples/js/client
Node Express Server A2A HTTP service implemented with Node/Express https://github.com/a2aproject/a2a-samples/tree/main/samples/js/server
☕ Java Custom Client Java client with streaming listener https://github.com/a2aproject/a2a-samples/tree/main/samples/java/custom_java_impl/client
Data Models Complete set of POJO data models https://github.com/a2aproject/a2a-samples/tree/main/samples/java/custom_java_impl/model
Custom Server Spring Boot A2A server implementation https://github.com/a2aproject/a2a-samples/tree/main/samples/java/custom_java_impl/server
Dice Agent (Multi-Transport) Agent supporting multiple transport protocols https://github.com/a2aproject/a2a-samples/tree/main/samples/java/agents/dice_agent_multi_transport
Magic 8-Ball (Security) Security-focused agent with OAuth2 https://github.com/a2aproject/a2a-samples/tree/main/samples/java/agents/magic_8_ball_security
Content Writer Agent Content generation agent https://github.com/a2aproject/a2a-samples/tree/main/samples/java/agents/content_writer
Content Editor Agent Content editing agent https://github.com/a2aproject/a2a-samples/tree/main/samples/java/agents/content_editor
Weather MCP Agent Weather agent with MCP integration https://github.com/a2aproject/a2a-samples/tree/main/samples/java/agents/weather_mcp
💠 .NET Basic A2A Demo Echo and Calculator server examples https://github.com/a2aproject/a2a-samples/tree/main/samples/dotnet/BasicA2ADemo
CLI Demo Command-line client and server demo https://github.com/a2aproject/a2a-samples/tree/main/samples/dotnet/A2ACliDemo
Semantic Kernel Demo Integration with Semantic Kernel https://github.com/a2aproject/a2a-samples/tree/main/samples/dotnet/A2ASemanticKernelDemo
🐍 Python CLI Host Command-line interface for interacting with A2A agents https://github.com/a2aproject/a2a-samples/tree/main/samples/python/hosts/cli
Hello World Recommended first-run "Hello World" scaffold https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/helloworld
LangGraph Agent Uses LangGraph to orchestrate multi-turn dialogue https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/langgraph
CrewAI Agent Demonstrates multi-role collaboration with CrewAI https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/crewai
Semantic Kernel Agent Orchestrates tools with Semantic Kernel https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/semantickernel
AG2 Agent Minimal AG2 mutual-call example https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/ag2
ADK Expense Reimbursement Multi-turn expense reimbursement with forms https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/adk_expense_reimbursement
Birthday Planner (ADK) Multi-step birthday-party planner with ADK https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/birthday_planner_adk
Azure AI Foundry Agent Example using Azure AI Foundry SDK https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/azureaifoundry_sdk
A2A MCP Integration Multi-agent collaboration with MCP servers https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/a2a_mcp
MCP without Framework Bare-metal MCP integration without frameworks https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/a2a-mcp-without-framework
Travel Planner Agent One-stop travel-planning agent https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/travel_planner_agent
Headless OAuth2 OAuth2 flow for headless agents https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/headless_agent_auth
Analytics Workflow Multi-agent orchestration for data-analytics https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/analytics
A2A Telemetry Collects and displays agent telemetry data https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/a2a_telemetry
Multiagent Host Comprehensive multi-agent orchestration example https://github.com/a2aproject/a2a-samples/tree/main/samples/python/hosts/a2a_multiagent_host
GitHub Agent Agent with GitHub toolset integration https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/github-agent
Veo Video Generator Generates video via Veo API https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/veo_video_gen
LlamaIndex File Chat Q&A retrieval over local files https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/llama_index_file_chat
Marvin Agent Builds domain agents with Marvin https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/marvin
MindsDB Agent Calls MindsDB for prediction and querying https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/mindsdb
🐹 Go Go Reference Impl Full A2A server + client implemented in Go https://github.com/a2aproject/a2a-samples/tree/main/samples/go

Quick Start First-time users: try TypeScript Movie Recommendation Agent, Python Hello World, or Go Go Reference Impl — minimal dependencies and the simplest startup commands.

Framework Integrations (Official Samples)

These show how agents built with specific frameworks can expose an A2A interface.

Language Agent Framework Agent Description Key A2A Features Demonstrated Link
🐍 Python LangGraph Multi-turn dialogue orchestration Tools, Streaming, Multi-turn Link
🐍 Python CrewAI Multi-role collaboration Non-textual Artifacts (Files) Link
🐍 Python Google ADK Expense reimbursement Multi-turn, Forms (DataPart) Link
🐍 Python Semantic Kernel Tool orchestration Tools, Multi-turn Link
🐍 Python AG2 Mutual agent calls Agent-to-Agent communication Link
🐍 Python Azure AI Foundry Azure AI integration Cloud deployment, Tools Link
🐍 Python LlamaIndex File Q&A retrieval RAG, Document processing Link
🚀 JS/TS Genkit Movie info / Code generation Tools, Artifacts (Files), Async Link
☕ Java Spring Boot Multi-transport agent HTTP/gRPC, Security Link
💠 .NET Semantic Kernel .NET AI integration Tools, .NET ecosystem Link

Community Implementations

SDKs & Libraries (by language)
  • Go
    • 🌟 a2a-go by @a2aproject Stars - Official Go SDK for the A2A Protocol with high-level server (a2asrv) and client (a2aclient) APIs, multi-transport support (gRPC, REST, JSON-RPC), extensible architecture, and a CLI tool for agent discovery and messaging.
    • 🌟 trpc-a2a-go by @trpc-group Stars - Go A2A implementation by the tRPC team featuring full client/server support, in-memory task management, streaming responses, session management, multiple auth methods (JWT, API Key, OAuth2), and comprehensive examples.
    • 🌟 a2a-go by @a2aserver Stars - A Go library for building A2A servers, with example implementations.
    • 🌟 a2a-go by @yeeaiclub Stars - Agent-to-Agent Protocol Implementation for Go, fully supports all methods of the A2A protocol, referring to the official Python SDK implementation.
    • 🌟 agent-sdk-go by @agenticenv Stars - Production-grade Go SDK for durable AI agents built on Temporal workflows. Features first-class A2A server/client, MCP, AG-UI streaming, sub-agents, human-in-the-loop, and OpenTelemetry. Survives crashes and deploys automatically.
  • Rust
    • 🌟 a2a-rs by @a2aproject Stars - Official Rust SDK for the A2A Protocol. Workspace-based implementation with core types, async client/server, gRPC/SLIMRPC bindings, SSE streaming, protobuf interop, and a CLI tool.
    • 🌟 ra2a by @qntx Stars - Comprehensive Rust SDK for A2A v1.0 with all 12 JSON-RPC methods, gRPC/SSE streaming, pluggable storage (PostgreSQL/MySQL/SQLite), OAuth 2.0/mTLS security, OpenTelemetry tracing, and composable Axum handlers.
    • 🌟 a2a-rs by @EmilLindfors Stars - An idiomatic Rust implementation following hexagonal architecture principles.
    • 🌟 Agentic by @jeremychone Stars - A Rust crate providing essential building blocks for agentic applications, with an ergonomic API for MCP and A2A support. (Work in Progress)
    • 🌟 jamjet-a2a by @jamjet-labs Stars - Standalone Rust SDK for A2A v1.0 with client, server, coordinator routing, and MCP bridge. TCK conformant (75/76 mandatory). Two crates: jamjet-a2a-types (pure types, zero I/O) + jamjet-a2a (full SDK with feature flags).
    • 🌟 a2a-rust by @tomtom215 - Pure Rust SDK for A2A v1.0 with quad transport (JSON-RPC/REST/WebSocket/gRPC), SSE streaming, agent card signing (JWS/ES256), pluggable stores (SQLite/PostgreSQL), multi-tenancy, and TCK conformance. Published on crates.io as a2a-protocol-sdk.
    • 🌟 awaken by @awakenworks Stars - A Rust agent runtime that serves AI SDK, CopilotKit, A2A, and MCP from the same backend, featuring type-safe state, streaming LLM failure recovery, and plugin extensibility. Published on crates.io.
    • 🌟 turul-a2a by @aussierobots Stars - Proto-first Rust SDK for A2A v1.0 with ergonomic server/client crates, pluggable storage (SQLite/PostgreSQL/DynamoDB), multi-transport support (HTTP/JSON-RPC/SSE/gRPC/AWS Lambda), JWT/API-key auth, and interoperability-tested against the official Go SDK. Published on crates.io.
  • Python
    • 🌟 a2a-python by @a2aproject Stars - Official Python SDK for running agentic applications as A2A servers following the Agent2Agent Protocol.
    • 🌟 a2a_min by @pcingola Stars - A minimalistic Python SDK for A2A communication.
    • 🌟 python-a2a by @themanojdesai Stars - An easy-to-use Python library for implementing the A2A protocol.
    • 🌟 fasta2a by @datalayer Stars - Framework-agnostic Python A2A server library that lets developers expose agents through ASGI with pluggable storage, broker, and worker components.
    • 🌟 A2AServer by @johnson7788 Stars - A Python server framework implementing Google's A2A protocol with MCP integration.
    • 🌟 adk-modular-architecture by @k-jarzyna Stars - A Python project demonstrating a modular architecture for ADK (Agent Development Kit) based agents, with A2A protocol considerations.
    • 🌟 codex-a2a by @liujuanjuan1984 Stars - Full A2A Protocol implementation for Codex CLI, providing a stateful, production-oriented agent service with standardized transport and lifecycle mapping.
    • 🌟 opencode-a2a by @Intelligent-Internet Stars - Full A2A Protocol implementation for OpenCode, providing a stateful A2A service with production-friendly deployment, auth, and session continuity.
    • 🌟 a2a-adapter by @hybroai Stars - Python SDK that converts agents from n8n, LangGraph, CrewAI, LangChain, Claude Code, Codex, Ollama, and more into A2A-compatible servers with auto-generated AgentCards and streaming support. Published on PyPI.
    • 🌟 distributed_a2a by @Barra-Technologies Stars - A Python library for building and orchestrating A2A agents with a registry service, router agent, routing client, and MCP management. MIT licensed and published on PyPI as distributed-a2a.
  • Ruby
    • 🌟 a2a by @wilsonsilva Stars - Ruby gem implementing A2A protocol data structures with serialization, validation, and case transformation support. Published on RubyGems.
    • 🌟 llm.rb by @llmrb Stars - Ruby's most capable AI runtime with A2A support via LLM::A2A, letting agents consume remote A2A agent skills as local tools over REST/JSON-RPC. Licensed under 0BSD.
    • 🌟 agent2agent by @general-intelligence-systems Stars - Full-featured Ruby SDK for A2A with server and client implementations, JSON-RPC 2.0 and HTTP+JSON/REST bindings, SSE streaming, SQLite persistence, push notifications, 47 protocol types, and extensive guides. Built on Falcon + Async for fiber-based concurrency. Published on RubyGems as agent2agent. Apache 2.0.
  • C++
    • 🌟 agent-protocol by @openJiuwen-ai Stars - C++ SDK for the Agent2Agent (A2A) Protocol (and MCP), providing implementations of agent communication protocols for C++ environments.
    • 🌟 a2a-cpp by @MisterVVP Stars - C++20 SDK for the Agent2Agent (A2A) Protocol with client/server APIs, discovery, REST/JSON-RPC/gRPC transports, streaming, authentication hooks, and CMake/vcpkg/Conan build integration.
  • Common Lisp
    • 🌟 mcp-lisp by @jsulmont Stars - Common Lisp SDK for MCP and A2A protocols with server, client, agent, and behavioral spec engine. Implements partial A2A v1.0 support (agent card discovery, messaging, skills, and task lifecycle). Features 438 unit tests, REPL agent with multi-provider LLM support, and agent swarm capabilities. Dual-licensed under MIT OR Apache-2.0.
  • C#/.NET
    • 🌟 a2a-dotnet by @a2aproject Stars - Official C#/.NET SDK for the A2A Protocol.
    • 🌟 a2adotnet by @azixaka Stars - A C#/.NET implementation of the A2A protocol.
    • 🌟 a2a-net by @neuroglia-io Stars - .NET implementation of the Agent2Agent (A2A) protocol to enable secure, interoperable communication between autonomous agents across frameworks and vendors.
  • JavaScript/TypeScript
    • 🌟 a2a-js by @a2aproject Stars - Official JavaScript SDK for the Agent2Agent (A2A) Protocol.
    • 🌟 a2a-ai-provider by @DracoBlue Stars - Community A2A provider for the Vercel AI SDK, enabling drop-in interoperability with A2A agents via generateText and streamText.
    • 🌟 nestjs-a2a by @thestupd Stars - A module for integrating the A2A protocol into NestJS applications.
    • 🌟 Artinet SDK by @the-artinet-project Stars - TypeScript (Node.js) A2A compliant server/client simplifying interoperable AI agent creation, focusing on DX and production-readiness.
    • 🌟 a2a-mesh by @oaslananka Stars - Production-ready TypeScript runtime for Google's A2A Protocol with multi-framework adapters, registry control plane, JWT/API-key auth, OpenTelemetry observability, CLI scaffolding, and testing toolkit. Published on npm.
    • 🌟 a2a-warp by @oaslananka Stars - Independent TypeScript runtime and toolkit for the A2A protocol, with server/client SDKs, registry, adapters for OpenAI/Anthropic/LangChain/Google ADK/LlamaIndex/CrewAI, CLI, MCP bridge, WebSocket/gRPC transports, and conformance tooling. Published on npm as @oaslananka/a2a-warp. Apache 2.0.
    • 🌟 a2a-reference-ts by @reaatech Stars - Production-ready TypeScript reference implementation of Google's A2A protocol with server framework (Express/Hono adapters), client SDK, bidirectional A2A ↔ MCP bridge, canonical Zod schemas, pluggable auth (OAuth2/JWT/API key), Redis/Postgres persistence, SSE streaming, and OpenTelemetry observability. Published on npm as @reaatech/*.
    • 🌟 agent-to-agent-ts by @A2A-tools Stars - Practical TypeScript A2A implementation with gRPC-first transport, AgentCard discovery, task lifecycle management, JSON Schema validation, HTTP/WebSocket helpers, and a bundled CLI. Node 22+.
  • PHP