Agent2Agent Protocol (A2A) alternatives

Google-led open protocol for agent-to-agent collaboration (announced 2025-04-09) — agent cards, RPCs, server-sent events. Launched with 50+ technology partners including Atlassian, MongoDB, Salesforce, ServiceNow. Full Agent2Agent Protocol (A2A) record →

  1. 1 LangChain (framework) Agent frameworks (no first-party memory layer)

    also in Agent frameworks (no first-party memory layer) · also open source · also self-hostable · also offered managed

    OSS ✓ Self-host ✓ Managed ✓ MCP ✓ ★ 149k released 2026-10-21 MIT (OSS framework) Compare with Agent2Agent Protocol (A2A) →

  2. 2 MCP Servers (Reference) Agent frameworks (no first-party memory layer)

    also in Agent frameworks (no first-party memory layer) · also open source · also self-hostable · also offered managed

    OSS ✓ Self-host ✓ Managed ✓ MCP ✓ ★ 92k released 2026-10-25 Apache-2.0 (transitioning from MIT… Compare with Agent2Agent Protocol (A2A) →

  3. 3 Cline (framework) Agent frameworks (no first-party memory layer)

    also in Agent frameworks (no first-party memory layer) · also open source · also self-hostable · also offered managed

    OSS ✓ Self-host ✓ Managed ✓ MCP ✓ ★ 68k Apache-2.0 Compare with Agent2Agent Protocol (A2A) →

  4. 4 CrewAI Agent frameworks (no first-party memory layer)

    also in Agent frameworks (no first-party memory layer) · also open source · also self-hostable · also offered managed

    OSS ✓ Self-host ✓ Managed ✓ MCP ✓ ★ 59k released 2026-10-24 MIT Compare with Agent2Agent Protocol (A2A) →

  5. 5 LlamaIndex (framework) Agent frameworks (no first-party memory layer)

    also in Agent frameworks (no first-party memory layer) · also open source · also self-hostable · also offered managed

    OSS ✓ Self-host ✓ Managed ✓ MCP ✓ ★ 53k released 2026-09-21 MIT Compare with Agent2Agent Protocol (A2A) →

  6. 6 LangGraph (orchestration) Agent frameworks (no first-party memory layer)

    also in Agent frameworks (no first-party memory layer) · also open source · also self-hostable · also offered managed

    OSS ✓ Self-host ✓ Managed ✓ MCP ✓ ★ 44k released 2026-10-26 MIT Compare with Agent2Agent Protocol (A2A) →

  7. 7 OpenAI Agents SDK Agent frameworks (no first-party memory layer)

    also in Agent frameworks (no first-party memory layer) · also open source · also self-hostable · also offered managed

    OSS ✓ Self-host ✓ Managed ✓ MCP ✓ ★ 30k released 2026-10-15 MIT Compare with Agent2Agent Protocol (A2A) →

  8. 8 Vercel AI SDK Agent frameworks (no first-party memory layer)

    also in Agent frameworks (no first-party memory layer) · also open source · also self-hostable · also offered managed

    OSS ✓ Self-host ✓ Managed ✓ MCP ✓ ★ 28k released 2026-10-26 Apache-2.0 Compare with Agent2Agent Protocol (A2A) →

Ranked by shared memory design (storage, retrieval, conflict handling, memory unit), same section and shared must-haves (open source, self-hosting, MCP), with adoption as a tie-breaker. ✓ confirmed · — no · ? not in the catalog yet. Want picks for your own requirements? Use the chooser. Checking a whole project? Check your stack.