Popular Agent Frameworks AI tools

20 category leaders in Agent Frameworks, selected from the full directory.

LangChain

  • Framework for LLM apps, tools, and agent orchestration.
  • Huge ecosystem of integrations and production examples.
  • LangSmith observability pairs with LangGraph agents.
  • Default starting library for agent developers.

LlamaIndex

  • Data framework for RAG, agents, and document workflows.
  • Indexes, retrieval, and query engines over private data.
  • Used to ground agents on enterprise documents.
  • LlamaParse adds agentic document parsing and extraction.

CrewAI

  • Role-based multi-agent teams in a few lines of Python.
  • Crews of specialized agents with task delegation.
  • Tens of millions of agent runs; Fortune 500 usage.
  • Go-to framework for readable multi-agent crews.

LangGraph

  • Graph runtime for stateful, durable agent workflows.
  • Checkpointing, interrupts, and human-in-the-loop.
  • Used by Klarna, Replit, Elastic, Cisco, GitLab.
  • Enterprise default for complex Python agent graphs.

PydanticAI

  • Type-safe Python agents built on Pydantic models.
  • Model-agnostic; MCP, A2A, and durable execution.
  • Logfire observability for traces and evals.
  • Go-to typed alternative to prompt-heavy stacks.

Microsoft Agent Framework

  • Microsoft's Python and .NET agent orchestration stack.
  • Successor path for AutoGen and Semantic Kernel.
  • Production workflows, deployment, and enterprise hooks.
  • Default Microsoft framework for multi-agent systems.

OpenAI Agents SDK

  • Lightweight multi-agent SDK from OpenAI.
  • Agents, tools, handoffs, guardrails, and tracing.
  • Python and TypeScript; 27k+ GitHub stars.
  • Production successor to experimental Swarm.

Google ADK

  • Google's open-source code-first agent framework.
  • Multi-agent workflows, tools, MCP, and eval hooks.
  • Python, TypeScript, Go, and Java SDKs.
  • 20k+ GitHub stars; model- and deployment-agnostic.

Mastra

  • TypeScript framework for agents, tools, and memory.
  • Workflows and evals aimed at production web apps.
  • Strong JS/TS alternative to Python-only stacks.
  • Leading TypeScript agent framework for product teams.

Claude Agent SDK

  • Official Anthropic SDK for Claude-powered agents.
  • Python agent loops with tools and platform hooks.
  • Aligned with Claude Code and Claude API patterns.
  • Default choice for Anthropic-first agent stacks.

AI SDK

  • Vercel TypeScript SDK for AI apps and agents.
  • Streaming, tools, and multi-step generation.
  • Works across major model providers.
  • Default agent toolkit for Next.js teams.

LiveKit Agents

  • Realtime voice and multimodal agent framework.
  • Python and Node SDKs on LiveKit transport.
  • Low-latency conversational and telephony agents.
  • Leading open stack for voice AI agents.

Pipecat

  • Open-source voice and multimodal agent pipelines.
  • Composable speech-to-speech and tool-calling flows.
  • From Daily; used as a base for realtime voice apps.
  • Open voice-agent stack alongside LiveKit Agents.

Agno

  • Python framework for multi-agent systems and tools.
  • AgentOS control plane runs agents in your own cloud.
  • Memory, retrieval, and team workflows in one stack.
  • Fast-growing open agent framework for production Python.

Letta

  • Agent framework built around long-term memory.
  • Stateful agents that persist context across sessions.
  • Roots in MemGPT research on memory management.
  • Git-based context repositories and memory-model research.

AG2

  • Open-source multi-agent AgentOS from AutoGen authors.
  • Successor community path as AutoGen goes maintenance.
  • Build systems of cooperating agents, not one-off prompts.
  • Key framework for AutoGen-lineage multi-agent apps.

Browser Use

  • Open-source agents that operate real web browsers.
  • Cloud browser infra priced for high-volume agent runs.
  • Widely adopted MIT core with strong task benchmarks.
  • Default builder stack for custom browser agents.

Strands Agents

  • Model-agnostic Python SDK for production AI agents.
  • Tool use, MCP, multi-agent workflows, OpenTelemetry.
  • Works with Bedrock, Anthropic, OpenAI, Gemini, and more.
  • AWS-backed default path for Bedrock agent builders.

smolagents

  • Hugging Face library for agents with minimal boilerplate.
  • CodeAgent runs tools via executable Python, not JSON schemas.
  • Model-agnostic across Hub, OpenAI, Anthropic, and local runtimes.
  • Official HF stack with strong open-source adoption.

CopilotKit

  • Open-source SDKs for agents embedded inside real apps.
  • Created AG-UI, the open agent-to-user interaction protocol.
  • AG-UI adopted by Google, Microsoft, Amazon, and Oracle.
  • 4M+ weekly downloads; $27M Series A in 2026.