Code Frameworks

Commercial / Proprietary

• Claude Agent SDK (Anthropic)
  • The harness behind Claude Code, as a library: file tools, shell execution, permissions, subagents, hooks, and in-process MCP servers
  • MIT-licensed, but built for Claude models only, so it isn’t listed as provider-agnostic
• Mastra
  • Hosted commercial layer, Mastra Platform (deployment, observability, hosted Studio), under the same brand as the open-source core (see Open Source)

Open Source / Provider-agnostic

• OpenAI Agents SDK
• LangChain
• LangGraph (LangChain)
  • Graph orchestration with checkpointed, resumable state. Its commercial deployment layer, LangSmith Deployment, is separately branded (§13 Agent Operations and Deployment)
• CrewAI
• Google ADK
• Microsoft Agent Framework
  • Successor to AutoGen and Semantic Kernel (see Legacy); Python and .NET
• LlamaIndex
  • LlamaIndex Workflows is its event-driven orchestration layer
• PydanticAI
• smolagents (Hugging Face)
• Mastra
  • Self-hostable open-source core; enterprise features and the hosted layer are commercial (see Commercial)
• Vercel AI SDK
• DSPy (Stanford)
• Haystack (deepset)
• AG2
  • Community-driven continuation of the AutoGen codebase; the classic autogen classes live on as AG2 Classic

Legacy / Decommissioned

• AutoGen (Microsoft)
  • Superseded by Microsoft Agent Framework 1.0 (April 3, 2026), built by the same team. Now in maintenance mode and community-managed; AG2 continues the codebase
• Semantic Kernel (Microsoft)
  • Superseded by Microsoft Agent Framework in the same release. Receives critical bug and security fixes only