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

v3.0.62026-09-04PythonApache-2.0
42.1k 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
60.8k Completely free Open source
CrewAI

CrewAI

CrewAI

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

v1.15.202026-09-04PythonMIT
58.1k 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==1.6.22026-09-04Python / JSMIT
145.8k Completely free Open source
LangGraph

LangGraph

LangChain

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

sdk==0.4.42026-08-27Python / JSMIT
41.1k Open source Free tier Paid

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

v0.22.02026-08-19PythonMIT
29.2k 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
29.2k 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.

v1.16.02026-08-27PythonMIT
13.8k Completely free Open source
Pydantic AI

Pydantic AI

Pydantic

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

v2.40.02026-09-05PythonMIT
19.7k 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.

v3.3.12026-08-21PythonMIT
37.8k 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

v0.14.242026-08-19PythonMIT
52.0k Open source Free tier Paid