A2A
Agent2Agent, an open protocol for agents built on different frameworks to communicate and work together.
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Use cases
About A2A
A2A is listed in our frameworks category and is aimed at builders. Agent2Agent, an open protocol for agents built on different frameworks to communicate and work together. Pricing, as the maker states it: Open standard. Maturity: Mature. We last checked the official link on 2026-10-16.
What is A2A?
A2A (Agent2Agent) is an open protocol for communication and interoperability between agentic applications. It lets agents built on different frameworks, by different companies and running on separate servers, collaborate as agents, not just as tools.
The protocol covers things like negotiating interaction modalities (text, forms, media) and collaborating securely, aiming to give agents a common language.
Sources: the official README and our directory listing, checked 2026-10-18. Official site: a2a-protocol.org.
Who is A2A for?
Developers and companies building agents that need to talk to agents built elsewhere.
A2A at a glance
- Open source: Yes (Apache License 2.0)
- GitHub: a2aproject/A2A · 26,231 stars (as of Oct 21, 2026)
Key features
- Open protocol for agent-to-agent communication
- Works across frameworks and vendors
- Negotiates modalities: text, forms, media
- Secure collaboration
A2A FAQ
What is A2A?
A2A (Agent2Agent) is an open protocol for communication and interoperability between agentic applications. It lets agents built on different frameworks, by different companies and running on separate servers, collaborate as agents, not just as tools.
Who is A2A for?
Developers and companies building agents that need to talk to agents built elsewhere.
Is A2A free?
A2A's pricing, as the maker states it: Open standard. Check the official site for current plans.
Is A2A open source?
Yes. A2A is released under the Apache License 2.0, according to its GitHub repository.
What are alternatives to A2A?
Similar tools include CrewAI, LangGraph, LlamaIndex, tRPC-Agent-Go, Embabel and Mastra.
A2A ratings and reviews
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A2A alternatives
Other frameworks tools in our directory. See all frameworks tools →
CrewAI
Framework for role-based multi-agent crews.
LangGraph
Framework for stateful, graph-based agent workflows.
LlamaIndex
Framework for agents over your data (RAG, document agents).
tRPC-Agent-Go
Go framework for production agent systems with graph workflows, tools, memory, A2A, AG-UI, MCP, evaluation and OpenTelemetry.
Embabel
Agent framework for the JVM from the creator of Spring.
Mastra
TypeScript framework for agents, workflows and RAG.
Related lists
🏆 Ranked in: CopilotKit alternatives
🔁 Listed in: CopilotKit alternatives
💲 Estimate API cost: compare per-request and monthly costs for GPT, Claude, Gemini and Grok models.
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