Open-source AI agent frameworks (2026)
Frameworks and SDKs for building your own agents, with public source code you can inspect and extend. Here are the top 25 of 83 from the AgentScout directory.
How we picked and ranked: tools are matched by category, the pricing each maker states and what each tool says it does. They are ranked by GitHub stars as recorded on each listing (link checks 2026-10-18); tools without a tracked repo follow, by listing maturity. No paid placements.
1. Hermes Agent (Nous Research)
Open-source agent harness; v0.21.7 stable shipped Oct 12, v0.22.0 RCs Oct 13-14.
Pricing (as stated): Open source · Active, frequent releases
2. DeepSeek Harness
DeepSeek's open-source agent harness with a local web UI, built so that every tool, model and scheduled task is a swappable plugin; still a developer preview.
Pricing (as stated): Open source · Mature
3. AutoGPT
One of the first autonomous agent projects, now a platform for building, deploying and running continuous AI agents that automate workflows.
Pricing (as stated): Open source + cloud · Mature
4. RAGFlow
Open-source RAG engine with deep document parsing and agent features for building grounded question-answering over your files.
Pricing (as stated): Open source + cloud · Mature
5. 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.
Pricing (as stated): Open source (MIT); model costs still apply · Active
6. MetaGPT
Multi-agent framework that assigns roles like product manager and engineer to LLM agents to build software.
Pricing (as stated): Open source · Mature
7. AutoGen
Microsoft's framework for multi-agent conversations, now archived and no longer maintained; Microsoft points new users to Microsoft Agent Framework.
Pricing (as stated): Open source · Archived (no longer maintained)
8. CrewAI
Framework for role-based multi-agent crews.
Pricing (as stated): Open source + paid cloud · Mature
9. LlamaIndex
Framework for agents over your data (RAG, document agents).
Pricing (as stated): Open source + paid cloud · Mature
10. LangGraph
Framework for stateful, graph-based agent workflows.
Pricing (as stated): Open source · Mature
11. Agno
Python framework and runtime for building, running and managing multi-agent systems with memory, knowledge and tools.
Pricing (as stated): Open source + cloud · Mature
12. OpenHuman
Lightweight open-source agent harness designed to run many agents cheaply on small servers.
Pricing (as stated): Open source · Mature
13. PageIndex
Document index for reasoning-based, vectorless RAG that lets agents navigate long documents like a table of contents.
Pricing (as stated): Open source + cloud · Mature
14. CopilotKit
Frontend stack for putting agents and generative UI into React and other apps, from the makers of the AG-UI protocol.
Pricing (as stated): Open source + cloud · Mature
15. AgentScope
Framework for building and running transparent multi-agent applications with visual debugging.
Pricing (as stated): Open source · Mature
16. Orkes
Orchestration platform built on Conductor for durable workflows and AI agents.
Pricing (as stated): Open source + cloud · Mature
17. LangChain Deep Agents
Library for long-running agents with subagents and skills; 0.7.23 (Oct 7) adds pinned_skills.
Pricing (as stated): Open source · Active
18. OpenAI Agents SDK (Python)
OpenAI's Python SDK for building multi-agent workflows; v0.23.0/0.23.1 released Oct 1-2.
Pricing (as stated): Open source · Mature, official SDK
19. smolagents
Hugging Face's minimal library for code-writing agents.
Pricing (as stated): Open source · Active
20. Haystack
Open-source orchestration framework for building production LLM apps, RAG and agents.
Pricing (as stated): Open source + cloud · Mature
21. Letta
Framework for stateful agents with long-term memory (formerly MemGPT).
Pricing (as stated): Open source + paid cloud · Mature
22. BabyAGI
Yohei Nakajima's experimental self-building agent framework that creates, stores and runs its own functions.
Pricing (as stated): Open source · Mature
23. Google ADK
Google's Agent Development Kit for building and deploying agents.
Pricing (as stated): Open source · Mature
24. Pydantic AI
Type-safe Python agent framework from the Pydantic team.
Pricing (as stated): Open source · Mature
25. Agent Lightning
Microsoft's lightweight trainer that improves existing agents with reinforcement learning through a model proxy, without rewriting the agent's tools or control flow.
Pricing (as stated): Open source · Mature
FAQ
What are the best open-source AI agent frameworks?
Ranked by tracked GitHub stars, the top open-source AI agent frameworks in our directory are Hermes Agent (Nous Research), DeepSeek Harness, AutoGPT, RAGFlow, Ruflo. Stars measure popularity, not fit, so compare a few against your own task.
How many open-source AI agent frameworks does AgentScout list?
83 tools match. This page shows the top 25. Pricing mix on this page: Open source (15), Open source + cloud (10).
How much do these tools cost?
Pricing is what each maker states on their site. Open-source tools are free to self-host but may need a paid model API key or offer paid cloud plans; freemium tools have a free plan with limits. Check each official site.
Where can I see every tool for building AI agents?
Our task page lists all 137 tools we match to building AI agents.
Related: All tools for building AI agents · Best AI Agent Frameworks · frameworks (83)
Similar searches: Python AI agent frameworks · TypeScript and JavaScript AI agent frameworks · Multi-agent frameworks
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Facts come from our directory listings; pricing is as each maker states it and can change. Check official sites before you choose.