Best AI agents for building AI agents (2026)

Open-source agent harness; v0.21.7 stable shipped Oct 12, v0.22.0 RCs Oct 13-14.

AutoGPT

One of the first autonomous agent projects, now a platform for building, deploying and running continuous AI agents that automate workflows.

RAGFlow

Open-source RAG engine with deep document parsing and agent features for building grounded question-answering over your files.

Ruflo

Open-source multi-agent meta-harness for Claude Code, Codex, and MCP clients; Oct 13 release adds Mods (mission workflows) and a single control plane with human approval.

MetaGPT

Multi-agent framework that assigns roles like product manager and engineer to LLM agents to build software.

AutoGen

Microsoft's framework for multi-agent conversations.

CrewAI

Framework for role-based multi-agent crews.

LlamaIndex

Framework for agents over your data (RAG, document agents).

LangGraph

Framework for stateful, graph-based agent workflows.

Agno

Python framework and runtime for building, running and managing multi-agent systems with memory, knowledge and tools.

OpenHuman

Lightweight open-source agent harness designed to run many agents cheaply on small servers.

PageIndex

Document index for reasoning-based, vectorless RAG that lets agents navigate long documents like a table of contents.

CopilotKit

Frontend stack for putting agents and generative UI into React and other apps, from the makers of the AG-UI protocol.

AgentScope

Framework for building and running transparent multi-agent applications with visual debugging.

Orkes

Orchestration platform built on Conductor for durable workflows and AI agents.

LangChain Deep Agents

Library for long-running agents with subagents and skills; 0.7.23 (Oct 7) adds pinned_skills.

OpenAI Agents SDK (Python)

OpenAI's Python SDK for building multi-agent workflows; v0.23.0/0.23.1 released Oct 1-2.

smolagents

Hugging Face's minimal library for code-writing agents.

Haystack

Open-source orchestration framework for building production LLM apps, RAG and agents.

A2A

frameworksOpen standard

Agent2Agent, an open protocol for agents built on different frameworks to communicate and work together.

Letta

Framework for stateful agents with long-term memory (formerly MemGPT).

BabyAGI

Yohei Nakajima's experimental self-building agent framework that creates, stores and runs its own functions.

Google ADK

Google's Agent Development Kit for building and deploying agents.

Pydantic AI

Type-safe Python agent framework from the Pydantic team.

Parlant

Framework for building reliable customer-facing agents with explicit behavior guidelines.

OpenFang

Open-source agent operating system for running autonomous agents.

CAMEL

CAMEL, one of the first multi-agent frameworks, for building role-playing agents and large agent societies.

AG-UI

frameworksOpen standard

Agent-User Interaction protocol for streaming agent state and events into frontend apps.

Trigger.dev

Platform for building and deploying durable background AI agents and workflows in TypeScript.

Microsoft Agent Framework

Microsoft's framework for building and orchestrating agents and multi-agent workflows in Python and .NET.

PocketFlow

Minimalist 100-line LLM framework for building agents and workflows.

Tambo

Generative UI SDK for React that lets agents render components.

Aden Hive

Multi-agent harness for production AI.

Spring AI Alibaba

Agentic AI framework for Java developers built on Spring AI.

Omnigent

Open-source agent framework and meta-harness that orchestrates Claude Code, Codex, Cursor and other agents together.

VoltAgent

TypeScript agent framework plus an engineering platform for building, observing and deploying AI agents.

OpenPipe

Reinforcement learning tooling, including the ART library, to train better agents.

PraisonAI

Multi-agent framework for building a self-improving AI workforce with little code.

Strands Agents

Strands open-source SDK for building production agent harnesses in Python and TypeScript.

Evolver

Self-evolving engine for AI agents with auditable genes, capsules and events.

Upsonic

Python framework for building autonomous AI agents.

Agent Squad

Framework for routing conversations across multiple specialized AI agents.

Flyte

Type-safe orchestration for agents, ML pipelines and inference on Kubernetes.

OpenEvolve

Open-source take on AlphaEvolve that uses LLM agents to evolve better code and algorithms.

Swarms

Enterprise multi-agent orchestration framework.

Open Multi-Agent

Self-hosted TypeScript agent runtime with durable approvals and verifiable run records.

Julep

Platform for durable AI agent workflows that can crash, resume and retry safely.

Genkit

Google's open-source framework for building agentic apps in JavaScript, Go, Dart and Python.

IntentKit

Self-hosted cloud cluster for running a team of collaborating AI agents.

TrueForge

Open-source agent harness runtime that turns an LLM into a working agent.

Marvin

Python library from Prefect for building AI agents and structured LLM workflows.

AgentScope Java

Java version of AgentScope for building distributed, long-running agents.

Open Agents

Vercel's open-source template for building cloud agents.

Cloudflare Agents

Cloudflare's SDK for building and deploying stateful AI agents on Workers.

AReaL

Reinforcement learning system for training LLM-based agents.

ZenML

MLOps and agent platform for building pipelines and deploying agents.

AG2

AG2, the community continuation of AutoGen, an open-source framework for multi-agent systems.

Prime Intellect

Decentralized compute and open RL environment hub for training agentic models.

Koog

JetBrains' Kotlin framework for building predictable, enterprise-ready AI agents on the JVM.

Docker Agent

Docker's agent builder and runtime for defining and running agents.

Agent Service Toolkit

Toolkit for running an agent service with LangGraph, FastAPI and Streamlit.

Embabel

Agent framework for the JVM from the creator of Spring.

RubyLLM

Ruby framework for working with LLMs, including chat, tools and agents, through one API.

Dagu

Self-hostable workflow orchestrator with a simple definition format and web UI, usable for agent jobs.

DocETL

System for agentic, LLM-powered document processing and ETL pipelines from UC Berkeley.

Langroid

Python framework for multi-agent programming with LLMs.

kagent

Cloud-native framework for running AI agents on Kubernetes.

fast-agent

Framework to build, run and evaluate agents with strong MCP, ACP and A2A support.

LazyLLM

Low-code framework for building multi-agent LLM applications.

TanStack AI

Type-safe, provider-agnostic TypeScript SDK for chat, tool calling and agents.

BotSharp

Multi-agent framework for .NET.

Ax

DSPy-style framework for building LLM programs and agents in TypeScript.

RAGEN

Reinforcement learning framework for multi-turn LLM agents.

AgentField

Build, run and scale AI agents like APIs and microservices.

Agentic Context Engine

Engine that lets agents learn from their own experience.

AgentFlow

Stanford's trainable agentic system where planner, executor, verifier and generator modules coordinate, with a Hugging Face demo.

IBM CUGA

IBM Research's configurable generalist agent (CUGA) for enterprise web and API tasks, with a live demo on Hugging Face Spaces.

Lyzr

frameworksFreemium

Enterprise agent studio and framework for building secure AI agents.

Viam

Software platform for building and operating robots and smart machines.

Orca Agent Engine

Open Apache-2.0 runtime to build, run, and govern managed agents with choice of harness (Claude Agent SDK, Codex, Pi) and model; open-sourced Oct 6, 2026 (Developer Preview).

Agentset

Open-source RAG platform for building agents and apps that answer accurately from your documents.

Mastra

TypeScript framework for agents, workflows and RAG.

Vercel AI SDK

personal agentsOpen source

TypeScript toolkit for building AI apps and agents.

Agent-Reach

researchOpen source

Lets an AI agent read and search sites like X, Reddit, YouTube and GitHub through one toolkit, without paid APIs.

Deer Flow

researchOpen source

ByteDance's open-source long-horizon agent harness that researches, codes and creates using sandboxes, memory and sub-agents.

Context7

MCP & infraFreemium

MCP server and platform that feeds coding agents up-to-date, version-specific library documentation.

Nanobot

Ultra-lightweight, self-hosted personal agent framework in Python with a web UI, tools, memory and MCP support.

CowAgent

personal agentsOpen source

Open-source personal assistant and agent harness that plans tasks, runs tools and skills and connects to chat apps.

Serena

MCP toolkit that gives coding agents semantic code retrieval and editing, like IDE features.

FastMCP

browser/computer useOpen source

Pythonic framework for building MCP servers and clients quickly.

Stagehand

Browser automation framework mixing code with natural-language actions.

MCP Python SDK

Official Python SDK for building Model Context Protocol servers and clients.

jcode

codingOpen source

High-performance coding agent harness written in Rust.

Pipecat

Open-source framework for voice and multimodal conversational agents.

MCP TypeScript SDK

browser/computer useOpen source

Official TypeScript SDK for building MCP servers and clients.

Agent-S

Open agentic framework that uses computers like a human through the GUI.

TEN Framework

Open-source framework for real-time multimodal voice agents, including the TEN Agent demo.

mcp-use

browser/computer useOpen source + cloud

Full-stack MCP framework for building MCP servers, MCP apps and agents that connect to them.

Mobilerun

LLM-agnostic agent framework for controlling Android and iOS devices with natural language.

Munder Difflin

codingOpen source

Free, open-source harness that runs Claude Code, Codex, Gemini CLI and other terminal agents together like an office.

Vision Agents

personal agentsOpen source

Stream's open framework for building real-time voice and video agents with any model.

Osaurus

Native macOS harness for AI agents with any model, memory and autonomous execution.

Honcho

MCP & infraOpen source + cloud

Memory library and service for building stateful agents that remember users.

Guardrails AI

evals & observabilityOpen source + cloud

Open-source framework for validating LLM inputs and outputs with configurable guardrails.

Agent Governance Toolkit

evals & observabilityOpen source

Microsoft toolkit for policy enforcement, identity and sandboxing for AI agents.

Open Connector

evals & observabilityOpen source

Open-source auth gateway connecting SaaS apps to AI agents via SDK, CLI and MCP.

Failproof AI

Observability and policy enforcement for AI agent harnesses.

Zotero MCP

MCP server that connects your Zotero research library to Claude and other assistants.

VibeSDK

app buildersOpen source

Cloudflare's open-source kit for running your own vibe-coding platform.

PPTAgent

productivityOpen source

Agentic framework that generates and refines PowerPoint presentations.

MCP C# SDK

Official C# SDK for building MCP servers and clients, maintained with Microsoft.

MCP Rust SDK

Official Rust SDK for the Model Context Protocol.

vocode

voiceOpen source + cloud

Open-source library for building voice-based LLM agents for phone calls and apps.

MCP Java SDK

Official Java SDK for MCP servers and clients.

OneCLI

Sandboxed agent harness for teams with secure credential handling.

PentestAgent

codingOpen source

Agent framework for black-box security testing and bug bounty work.

MiroFlow

researchOpen source

Research agent framework with web UI supporting MiroThinker and other models.

Stripe Agent Toolkit

Stripe's agent toolkit and MCP server for customers, payments and billing.

Voiceloop