Best agent frameworks and SDKs (2026)

1. 1.FastAPIModern Python APIs at startup speed

   Free / OSS · OSS/MIT · 103k GitHub stars

   VerdictThe Python API framework you will actually enjoy.

   CatchThe ecosystem assumes you will integrate pieces yourself—no batteries-included ORM or auth. Async programming has its own learning curve.

2. 2.TyperCLI apps with type hints and zero effort

   Free / OSS · OSS/MIT · 20.1k GitHub stars

   VerdictCLI tools in minutes instead of hours.

   CatchComplex CLI patterns sometimes fight the abstraction. Very dynamic interfaces may need lower-level Click access.

3. 3.LitestarThe FastAPI alternative with batteries

   Free / OSS · OSS/MIT · 8.5k GitHub stars

   VerdictMore opinionated FastAPI alternative worth considering.

   CatchSmaller community means fewer tutorials and Stack Overflow answers. Some FastAPI extensions need equivalents.

4. 4.BeeAI FrameworkApache-2.0 production agents in Python and TypeScript — MCP + A2A

   Free / OSS · Apache-2.0 · 3.4k GitHub stars

   VerdictApache-2.0 dual-language agent framework. MCP/A2A serve built in; you own ops and models.

   CatchVs Agno / VoltAgent / Google ADK (agent kits) and mcp-use / FastMCP (MCP server kits): BeeAI is dual-language agent framework + protocol serve, not a coding CLI and not a managed tool catalog. IBM open-source notice says community maintenance posture — treat it as OSS you own, not an IBM product SLA. A2A server is Python-first today.

5. 5.Microsoft Agent FrameworkMIT successor to AutoGen + Semantic Kernel — Python and .NET

   Free / OSS · OSS/MIT · 14.2k GitHub stars

   VerdictMIT Microsoft agent SDK. Prefer over AutoGen for new builds; watch Azure meters in prod.

   CatchVs AG2 (community AutoGen fork), LangGraph (graph orchestration), and Google ADK: MAF is Microsoft’s enterprise-shaped multi-agent SDK, not a coding seat. Foundry hosted agents and Azure model meters are paid paths — OSS framework still runs with BYO providers. AutoGen is maintenance-only; start new projects here, not there.

6. 6.Strands AgentsApache-2.0 model-driven agent SDK from AWS — Python and TypeScript

   Free / OSS · Apache-2.0 · 8.9k GitHub stars

   VerdictApache-2.0 AWS agent harness. Model-driven + MCP; Bedrock optional, not mandatory.

   CatchVs Agno / OpenAI Agents SDK / Microsoft Agent Framework: Strands is AWS-born harness with Bedrock gravity, not a coding CLI and not a React copilot UI. Bedrock/AgentCore paths meter when you leave local/BYO. Bring your own model spend either way.

7. 7.OpenAI Agents SDKMIT multi-agent workflows — tools, handoffs, tracing, MCP

   Free / OSS · OSS/MIT · 30.1k GitHub stars

   VerdictMIT OpenAI agent workflow SDK. Build multi-agent loops; API spend is separate.

   CatchVs openai-codex-cli (terminal coding agent), Vercel AI SDK (app AI primitives), and Microsoft Agent Framework: this is the workflow SDK, not the Codex CLI seat. OpenAI API keys and hosted tools meter; sandbox/realtime extras add surface area. Do not confuse with ChatGPT product seats.

8. 8.CopilotKitMIT agent-native UI layer — React copilots, AG-UI, MCP

   Free / OSS · Freemium · 38.1k GitHub stars

   VerdictMIT agent UI layer. Self-host free; Cloud Developer free forever is real but capped.

   CatchVs Vercel AI SDK (primitives) and Mastra/LangGraph (backend agent runtimes): CopilotKit is the user-facing agent UI/protocol layer, not the orchestration brain. Pro/Team Cloud and VPC are paid when you outgrow Developer free forever. Self-host keeps the MIT path.

9. 9.GriptapeApache-2.0 Python agents, pipelines, RAG — MCP tools too

   Free / OSS · Apache-2.0 · 2.6k GitHub stars

   VerdictApache-2.0 Python agent/RAG framework. MCP as tools; Cloud free tier is metered, not forever.

   CatchVs LangChain/LangGraph and CrewAI: Griptape is a structured Python agent/RAG framework, not a coding CLI. Cloud Developer free tier needs a payment method on file and meters after small included quotas — pitch the OSS framework first, not Cloud as free forever.

10. 10.colibrìApache-2.0 pure-C zero-deps MoE streamed from disk

    Free / OSS · Apache-2.0 · 42.8k GitHub stars

    VerdictApache-2.0 pure-C MoE engine. Disk-streamed experts vs Ollama/vLLM; hardware-honest.

    CatchVs Ollama/vLLM (local serve / high-throughput GPU serving): colibrì is research-grade MoE disk-streaming for models that do not fit, not the everyday pull-and-chat DX of Ollama or the production serving stack of vLLM. research/HW-heavy — expect fast NVMe, large model containers (hundreds of GB), and tokens/sec that track your disk hierarchy.

Also reviewed (9)

• aclif — Agent CLI framework — one grammar across SaaS providers
• Univer — Embeddable Office runtime where agents and humans share documents
• tRPC-Agent-Go — Apache-2.0 Go production agent framework — GraphAgent, MCP, A2A
• Dapr Agents — Apache-2.0 CNCF Dapr durable agent workflows on Kubernetes
• FrontierAgent — Apache-2.0 agent runtime + TUI with Agent Team board
• BAML — Apache-2.0 typed DSL for LLM functions — schema-guaranteed outputs
• Claude Agent SDK — MIT first-party Anthropic SDK — Claude Code agent loop in your app
• Agent Client Protocol — Apache-2.0 LSP-for-agents: one protocol so any editor can talk to any coding agent
• AgentScope — Apache-2.0 agent framework for capable LLMs