Agent Frameworks

The backbone of an agent: these libraries run the reason–act loop, call tools, manage state, and coordinate one or many agents. Pick based on how much structure you want — from a single typed call to a full multi-agent graph.

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Multi-Agent Orchestration

Coordinate multiple agents, tools, and reasoning steps into one workflow.

Agno

Agno

Agno

High-performance framework and runtime (AgentOS) for multi-agent systems

v2.8.02026-07-20PythonApache-2.0
41.4k Open source Free tier Paid
AutoGen

AutoGen

Microsoft

Microsoft's multi-agent conversation framework (maintenance-only; new work moved to Microsoft Agent Framework)

Maintenance onlyNo updates in 6+ monthspython-v0.7.52025-09-30PythonMIT
59.9k Completely free Open source
CrewAI

CrewAI

CrewAI

Role-based multi-agent orchestration — assemble a crew of agents with goals and tasks.

v1.15.52026-07-20PythonMIT
56.0k Open source Free tier Paid
LangChain

LangChain

LangChain

The original LLM-app framework — standard model/tool interfaces, hundreds of integrations, and the create_agent prebuilt that compiles to a LangGraph agent

langchain-core==1.5.02026-07-21Python / JSMIT
142.4k Completely free Open source
LangGraph

LangGraph

LangChain

Graph-based orchestration for stateful, multi-step agents with branching, loops, and human-in-the-loop

v1.2.92026-07-10Python / JSMIT
37.9k Open source Free tier Paid

OpenAI's lightweight SDK for agents with tools, handoffs, and guardrails

v0.18.32026-07-17PythonMIT
28.1k Completely free Open source
smolagents

smolagents

Hugging Face

Hugging Face's minimal library for agents that act by writing and running code

v1.26.02026-05-29PythonApache-2.0
28.5k Completely free Open source

Structured Output & Typing

Coerce model responses into validated, typed data structures.

instructor

567 Labs

Structured, validated outputs from any LLM — define a Pydantic model and get a typed object back.

v1.15.42026-06-28PythonMIT
13.6k Completely free Open source
Pydantic AI

Pydantic AI

Pydantic

Type-safe agent framework from the Pydantic team — structured, validated results with any model

v2.16.02026-07-23PythonMIT
18.7k Completely free Open source

Prompt Optimization

Program and automatically optimize prompts instead of hand-tuning them.

DSPy

DSPy

Stanford NLP

Program — don't prompt — language models; declare modules and let DSPy compile and optimize the prompts.

v3.2.12026-05-05PythonMIT
36.3k Completely free Open source

RAG & Data Frameworks

Frameworks for retrieval-augmented generation and data-centric agents

LlamaIndex

LlamaIndex

LlamaIndex

Data framework for building RAG pipelines and document agents over your own data

v0.14.232026-06-24PythonMIT
51.0k Open source Free tier Paid