Agent2Agent (A2A) Protocol
An open protocol for agents to discover and talk to each other.
A2A lets agents built on different frameworks and vendors find each other through Agent Cards and hand off work as tasks with a defined lifecycle. Google introduced it in 2025 and it is now governed under the Linux Foundation; it complements MCP, which connects agents to tools.
- Vendor
- Linux Foundation (Google-originated)
- Category
- Agent frameworks
- Pricing
- Open source
- Open source
- Yes
- License
- Apache 2.0
- Platforms
- Python, TypeScript, Java, Go, C#
- Launched
- 2025
- Website
- a2a-protocol.org
Features
- Agent Cards discovery
- Task lifecycle
- Streaming updates
Best for
- Agents
- Enterprise
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- OpenAI Agents SDK — OpenAI. Lightweight multi-agent workflows with handoffs.
- CrewAI — CrewAI. Role-based multi-agent crews.
- Agent Development Kit — Google. Google’s open-source framework for multi-agent systems.
- Agno — Agno. Python framework and runtime for multi-agent systems.
- Pydantic AI — Pydantic. Type-safe agent framework for Python.