Best Of · 10 frameworks
Open-source frameworks and platforms for building AI agents. This page compares tools for developers who want to build their own agent systems — not pre-built AI assistants. Every framework listed here has a profile in our directory with full details.
All 10 frameworks are open source. Browse all Agent Frameworks →
| Framework | Best for | Language | Setup | Pricing | Hosted | API | Docs |
|---|---|---|---|---|---|---|---|
| LangGraph LangChain | Stateful multi-agent workflows with human-in-the-loop control | Python | medium | Free | No | No | Yes |
| CrewAI CrewAI | Orchestrating autonomous agent teams for enterprise tasks | Python | medium | Freemium | Yes | Yes | Yes |
| AutoGen Microsoft | Multi-agent conversations in Python and .NET | Python, .NET | medium | Free | No | No | Yes |
| Semantic Kernel Microsoft | Adding AI agents to .NET, Python, and Java apps | Python, .NET, Java | medium | Free | No | No | Yes |
| LlamaIndex LlamaIndex | Document-grounded agents and retrieval-augmented generation | Python | medium | Freemium | Yes | Yes | Yes |
| Pydantic AI Pydantic | Type-safe Python agents with validated structured outputs | Python | medium | Free | No | No | Yes |
| Smolagents Hugging Face | Minimal code-first agents with Hugging Face ecosystem | Python | medium | Free | No | No | Yes |
| Dify LangGenius | No-code agentic workflows and RAG pipelines | Not listed | easy | Freemium | Yes | Yes | Yes |
| Flowise FlowiseAI | Visual drag-and-drop agent and RAG workflow building | Not listed | easy | Freemium | Yes | Yes | Yes |
| Mastra Mastra | TypeScript-first AI agents and workflows for Node.js teams | TypeScript | medium | Free | No | Yes | Yes |
An open-source Python framework for building stateful, multi-agent workflows with human-in-the-loop controls and persistent memory.
Best for
Stateful multi-agent workflows with human-in-the-loop control
Not ideal for
Non-developers or teams needing a hosted no-code agent builder
An open-source framework and hosted platform for building teams of AI agents that collaborate on complex tasks autonomously.
Best for
Orchestrating autonomous agent teams for enterprise tasks
Not ideal for
Solo developers who need a lightweight single-agent setup
A Microsoft framework for building multi-agent AI applications where agents collaborate through structured conversations.
Best for
Multi-agent conversations in Python and .NET
Not ideal for
New projects — Microsoft recommends their newer Agent Framework instead
A Microsoft SDK for building, orchestrating, and deploying AI agents and multi-agent systems in .NET, Python, and Java.
Best for
Adding AI agents to .NET, Python, and Java apps
Not ideal for
Non-developers or teams outside the Microsoft ecosystem
An open-source framework for building document-grounded AI agents and retrieval-augmented generation pipelines.
Best for
Document-grounded agents and retrieval-augmented generation
Not ideal for
General-purpose agent orchestration without a document/data focus
A Python agent framework with built-in validation and structured outputs, built by the team behind Pydantic.
Best for
Type-safe Python agents with validated structured outputs
Not ideal for
Non-Python developers or teams needing a visual agent builder
A barebones Python library where agents think and act by writing code, built by Hugging Face.
Best for
Minimal code-first agents with Hugging Face ecosystem
Not ideal for
Complex multi-agent orchestration or teams needing visual tooling
An open-source platform for building agentic workflows and RAG pipelines with a visual no-code interface.
Best for
No-code agentic workflows and RAG pipelines
Not ideal for
Developers who need full code-level control over agent behaviour
An open-source drag-and-drop platform for building AI agents, RAG systems, and multi-agent workflows visually.
Best for
Visual drag-and-drop agent and RAG workflow building
Not ideal for
Developers who prefer code-first agent frameworks with full programmatic control
An open-source TypeScript framework for building, deploying, and observing AI agents and workflows.
Best for
TypeScript-first AI agents and workflows for Node.js teams
Not ideal for
Python-first teams or those needing a visual no-code builder
Most frameworks are Python-first. If your team uses TypeScript, Mastra is currently the only dedicated option. For .NET or Java, Semantic Kernel is the strongest choice.
Dify and Flowise offer drag-and-drop interfaces — faster to prototype, but less flexible for custom logic. The rest are code-only and give you full control.
If you need multiple agents working together, LangGraph, CrewAI, and AutoGen are designed for multi-agent orchestration. Pydantic AI and Smolagents are better for single-agent or simple pipeline use cases.
CrewAI, Dify, Flowise, and LlamaIndex offer cloud-hosted options alongside self-hosting. The others are self-hosted only — you manage your own infrastructure.
An AI agent framework is a library or platform that provides the building blocks for creating AI agents — programs that can reason, use tools, and take actions autonomously. Frameworks handle orchestration, state management, and LLM integration so you can focus on defining agent behaviour.
Most frameworks in this list are Python-first: LangGraph, CrewAI, Pydantic AI, Smolagents, and AutoGen all support Python. LangGraph and CrewAI are the most full-featured; Pydantic AI is strongest for type safety; Smolagents is the most minimal.
Dify and Flowise both offer drag-and-drop visual interfaces for building agent workflows without writing orchestration code. The other frameworks are code-only.
Mastra is the only TypeScript-native framework in this list. It integrates with Next.js, Express, and Hono. Semantic Kernel also has some TypeScript/JavaScript support alongside .NET and Python.
All 10 are open source. LangGraph, AutoGen, Semantic Kernel, Pydantic AI, Smolagents, and Mastra are fully free. CrewAI, Dify, Flowise, and LlamaIndex offer free open-source cores with optional paid cloud hosting.
See the full Agent Frameworks category with detailed profiles.
Browse all Agent Frameworks →