Last verified: 2026-07-30
You're building an agent. Which framework do you reach for?
| SDK | Vendor | Best for | Watch out for |
|---|---|---|---|
| OpenAI Agents SDK | OpenAI | OpenAI-only stacks, handoffs, guardrails | Lock-in to OpenAI models |
| Anthropic Claude Agent SDK | Anthropic | Long-horizon agents, computer use, file sandboxing | Anthropic-only |
| LangGraph | LangChain | Stateful multi-agent graphs, complex orchestration | Steeper learning curve |
| CrewAI | CrewAI | Role-based multi-agent, rapid prototyping | Less control over execution |
| AutoGen | Microsoft | Async multi-agent, event-driven | Heavier; .NET heritage shows |
| Google ADK | Vertex-native, Google Workspace integration | Google-cloud-centric | |
| Pydantic AI | Pydantic | Type-safe structured outputs, minimal abstraction | Less out-of-the-box agent logic |
| Instructor | jxnl | Pure structured output extraction | Not an agent framework |
| LlamaIndex | LlamaIndex | RAG-first; agents as a secondary concern | Less polished for pure-agent work |
| Mastra | Mastra | TypeScript-native, Vercel-style | TS-only |
| Vercel AI SDK | Vercel | Streaming UIs in Next.js | TS-only, less backend depth |
graph TD
A[Need an agent framework?] -->|No, just structured output| B[Instructor or Pydantic AI]
A -->|Yes| C{Single vendor?}
C -->|OpenAI| D[OpenAI Agents SDK]
C -->|Anthropic| E[Claude Agent SDK]
C -->|Multi-vendor| F{Need stateful multi-agent graphs?}
F -->|Yes| G[LangGraph]
F -->|No| H{Team preference?}
H -->|Python, simple| I[CrewAI]
H -->|Python, type-safe| J[Pydantic AI]
H -->|TypeScript| K[Mastra or Vercel AI SDK]
If you don't know, pick OpenAI Agents SDK (Python) for greenfield work in 2026. It's the simplest path to a production agent. Switch to LangGraph when you need durable, multi-agent state machines.
- OpenAI Agents SDK — verified 2026-07-30
- Anthropic Claude Agent SDK — verified 2026-07-30
- LangGraph — verified 2026-07-30