175 listed
Harnesses & SDKs
Frameworks and SDKs for building agents: the Claude Agent SDK, OpenAI Agents SDK, LangGraph, CrewAI and many more. Each page lists languages, packages, MCP and A2A support and how it orchestrates agents, with a link to the page every fact came from.
Showing 1–7 of 7
| Name | Language | Stars | Downloads / month (approx.) | MCP | A2A | Multi-agent |
|---|---|---|---|---|---|---|
| atmosphere Java runtime for AI agents that streams tokens and tool events over WebSocket, SSE or gRPC, with human approvals. | Java | 3.8K | — | Built in | Built in | Yes |
| Google Agent Development Kit (ADK) Open-source toolkit for building, evaluating and deploying agents in Python, TypeScript, Go, Java and Kotlin, tuned for Gemini but model-agnostic. | Python, TypeScript, Go, Java, Kotlin | 22K | ~10.1M | Built in | Not stated | Yes |
| Spring AI Alibaba Java framework for agentic, workflow and multi-agent AI apps, with graph workflows, MCP and A2A support. | Java | 11.1K | — | Built in | Built in | Yes |
| Koog Kotlin and Java framework for AI agents with tools, graph workflows, MCP, streaming and multiplatform targets. | Kotlin, Java | 4.6K | — | Built in | Not stated | — |
| attestix Python toolkit for signed identities, verifiable credentials and delegated authority for AI agents, with MCP and REST interfaces. | Python, JavaScript, Go, Java | 839 | ~690 | Built in | Not stated | — |
| Semantic Kernel Model-agnostic SDK for building agents and multi-agent systems in Python, .NET and Java; Microsoft names Agent Framework as its successor. | Python, C#, Java | 28.7K | ~332.1K | Built in | Not stated | Yes |
| ADK for Java Code-first Java toolkit for building and testing AI agents, with multi-agent hierarchies, a dev UI and Maven packages. | Java | 1.8K | — | Built in | Built in | Yes |