ToolRankBest open-source Python AI agent frameworks
Updated 17 Oct 2026 · Prices from vendor pages only · How we rank →
The short answer
Each of these is a code-first agent framework you can install in Python, with a free open-source or free tier to start. CrewAI comes first: multi-agent orchestration framework plus hosted platform. The cheapest verified paid plan here is LlamaIndex Starter ($50/month). 7 of the 7 have a free plan we could confirm. Every price below is from the vendor’s own page, checked 16–17 Oct 2026.
Ranked shortlist
- CrewAI: Multi-agent orchestration framework plus hosted platform. Plan: Basic: Free
50 executions/month - OpenAI Agents SDK: OpenAI's lightweight framework for multi-agent workflows. Plan: Open source (MIT)
- Google ADK: Google's open-source Agent Development Kit. Plan: Open source (Apache-2.0)
- Microsoft Agent Framework: Microsoft's open-source successor to AutoGen and Semantic Kernel agents. Plan: Open source (MIT)
- LlamaIndex: Framework and cloud for agents over your documents. Plan: Free: $0/month
- Pydantic AI: Type-safe Python agent framework from the Pydantic team. Plan: Open source (MIT)
- Agno: Open-source Python framework and runtime for multi-agent systems. Plan: Free: $0/month
Order follows ToolRank’s editorial ranking in Automation & Agents, filtered to tools that fit this page. Anything we couldn’t confirm on a vendor page says “Not yet verified”.
Side by side
| Rank | Tool | Relevant plan | Starting price | Free plan | Best for | Main limitation | Last checked |
|---|---|---|---|---|---|---|---|
| #1 | CrewAI | Basic: Free 50 executions/month | Not yet verified | Basic: free, 50 workflow executions/month | Developers building multi-agent workflows | Paid self-serve tier not shown; Enterprise is custom | 16 Oct 2026 |
| #2 | OpenAI Agents SDK | Open source (MIT) | Not yet verified | Open source (MIT) | Developers building multi-agent workflows with tools and handoffs | You pay your model provider for usage | 17 Oct 2026 |
| #3 | Google ADK | Open source (Apache-2.0) | Not yet verified | Open source (Apache-2.0) | Developers building agents on Gemini and Google Cloud | You pay your model provider for usage | 17 Oct 2026 |
| #4 | Microsoft Agent Framework | Open source (MIT) | Not yet verified | Open source (MIT) | .NET and Python teams taking agents to production on Microsoft's stack | You pay your model provider for usage | 17 Oct 2026 |
| #5 | LlamaIndex | Free: $0/month | $50/month (Starter) | Free: $0/month | Document parsing and retrieval for LLM apps | Cloud credits limit parsing volume | 16 Oct 2026 |
| #6 | Pydantic AI | Open source (MIT) | Not yet verified | Open source (MIT) | Python developers who want type-safe agents | A code library: you supply model API keys and hosting | 17 Oct 2026 |
| #7 | Agno | Free: $0/month | $150/month (Pro) | Free: $0/month runtime, you host it | Python developers running agents on their own infrastructure | Control plane needs Pro | 16 Oct 2026 |
Prices as listed by each vendor on the last-checked date, USD, before tax. Plans and limits change, so follow the sources below.
Who should pick which
Pick CrewAI for developers building multi-agent workflows (Basic: Free). Watch out: paid self-serve tier not shown; Enterprise is custom. Pick OpenAI Agents SDK for developers building multi-agent workflows with tools and handoffs (free plan: Open source (MIT)). Watch out: you pay your model provider for usage. Pick Google ADK for developers building agents on Gemini and Google Cloud (free plan: Open source (Apache-2.0)). Watch out: you pay your model provider for usage. Pick Microsoft Agent Framework for .NET and Python teams taking agents to production on Microsoft's stack (free plan: Open source (MIT)). Watch out: you pay your model provider for usage. Pick LlamaIndex for document parsing and retrieval for LLM apps (Free: $0/month). Watch out: cloud credits limit parsing volume. Pick Pydantic AI for python developers who want type-safe agents (free plan: Open source (MIT)). Watch out: a code library: you supply model API keys and hosting. Pick Agno for python developers running agents on their own infrastructure (Free: $0/month). Watch out: control plane needs Pro.
FAQ
Which of these is cheapest?
LlamaIndex Starter ($50/month) is the lowest paid price we verified on this list (https://www.llamaindex.ai/pricing, checked 16 Oct 2026). Check the vendor page for tax, billing period and usage limits.
Which of these have a free plan?
CrewAI: Basic: free, 50 workflow executions/month; OpenAI Agents SDK: Open source (MIT); Google ADK: Open source (Apache-2.0); Microsoft Agent Framework: Open source (MIT); LlamaIndex: Free: $0/month; Pydantic AI: Open source (MIT); Agno: Free: $0/month runtime, you host it.
How were these tools chosen?
They are the tools in ToolRank's rankings with a Python framework listed on the vendor's site or repository, confirmed on the vendor's own website on 16–17 Oct 2026. Tools we could not verify are left out rather than guessed, and anything unconfirmed is marked Not yet verified.
Sources
- CrewAI: CrewAI pricing checked 16 Oct 2026
- OpenAI Agents SDK: OpenAI Agents SDK GitHub repository checked 17 Oct 2026
- Google ADK: Google ADK GitHub repository checked 17 Oct 2026
- Microsoft Agent Framework: Microsoft Agent Framework GitHub repository checked 17 Oct 2026
- LlamaIndex: LlamaIndex pricing checked 16 Oct 2026
- Pydantic AI: Pydantic AI GitHub repository checked 17 Oct 2026
- Agno: Agno pricing checked 16 Oct 2026
Related comparisons
Profiles: CrewAI · OpenAI Agents SDK · Google ADK · Microsoft Agent Framework · LlamaIndex · Pydantic AI · Agno
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