ToolRankBest AI agent frameworks for developers
Updated 16 Oct 2026 · Prices from vendor pages only · How we rank →
The short answer
These are code-first frameworks or platforms for building AI agents, each with a free way to start. CrewAI comes first: multi-agent orchestration framework plus hosted platform. The cheapest verified paid plan here is LlamaIndex Starter ($50/month). 5 of the 5 have a free plan we could confirm. Every price below is from the vendor’s own page, checked 16 Oct 2026.
Ranked shortlist
- CrewAI: Multi-agent orchestration framework plus hosted platform. Plan: Basic: Free
50 executions/month - LlamaIndex: Framework and cloud for agents over your documents. Plan: Free: $0/month
- Mastra: Open-source TypeScript agent framework. Plan: Starter: $0/month
100K observability events - Langflow: Open-source visual builder for agents and RAG. Plan: Free and open source, plus a free cloud account
- 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 | 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 |
| #3 | Mastra | Starter: $0/month 100K observability events | $250/month (Teams) | Starter: free for everyone; self-hosted open-source framework | TypeScript developers building agents | Cloud Teams plan starts high | 16 Oct 2026 |
| #4 | Langflow | Free and open source, plus a free cloud account | Not yet verified | Free and open source, plus a free cloud account | Building and deploying agents and MCP servers visually | Cloud limits are not published on the homepage | 16 Oct 2026 |
| #5 | 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 LlamaIndex for document parsing and retrieval for LLM apps (Free: $0/month). Watch out: cloud credits limit parsing volume. Pick Mastra for TypeScript developers building agents (Starter: $0/month). Watch out: cloud Teams plan starts high. Pick Langflow for building and deploying agents and MCP servers visually (free plan: Free and open source, plus a free cloud account). Watch out: cloud limits are not published on the homepage. 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; LlamaIndex: Free: $0/month; Mastra: Starter: free for everyone; self-hosted open-source framework; Langflow: Free and open source, plus a free cloud account; Agno: Free: $0/month runtime, you host it.
How were these tools chosen?
They are the tools in ToolRank's rankings with a developer framework with a free tier or open-source edition, confirmed on the vendor's own website on 16 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
- LlamaIndex: LlamaIndex pricing checked 16 Oct 2026
- Mastra: Mastra pricing checked 16 Oct 2026
- Langflow: Langflow pricing checked 16 Oct 2026
- Agno: Agno pricing checked 16 Oct 2026
Related comparisons
Profiles: CrewAI · LlamaIndex · Mastra · Langflow · Agno
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