Tool Category
Best AI Agent Development Tools
7 tools compared on real pricing, genuine strengths, and the limitations that only show up after you buy.
The short answer
We track 7 Agent Development tools, 7 of which have a free or freemium tier you can evaluate without a sales call. Our picks are LangGraph, CrewAI and Haystack. Each entry below lists real pricing, what it is genuinely good at, and the limitations that only show up after you buy.
Pricing at a glance
| Tool | Pricing model | What it costs |
|---|---|---|
| LangGraph | freemium | Open-source framework, free to use. Paid tiers apply to the surrounding LangSmith platform, not the framework itself. |
| CrewAI | freemium | Open-source framework, free. CrewAI also offers a paid enterprise platform for deployment and management. |
| Haystack | freemium | Open-source framework is free. The deepset AI Platform is a paid, enterprise-oriented managed offering. |
| LlamaIndex | freemium | Open-source framework is free. LlamaCloud (managed parsing and indexing) is sold on usage-based paid plans. |
| Microsoft AutoGen | free | Open-source (MIT), free to use. You pay only for the underlying model API calls. |
| OpenAI AgentKit | freemium | No separate platform fee. Agent Builder design is free; you pay standard OpenAI API model and storage rates for execution. As a reference point, GPT-5.2 runs roughly $1.75 per million input tokens and $14 per million output tokens, with GPT-5 mini at about $0.25 per million input tokens. |
| Semantic Kernel | free | Open-source (MIT), free. Costs come from the model APIs you call. |
All 7 Agent Development tools
LangGraph
Agent DevelopmentA low-level orchestration framework for building stateful, multi-step agent workflows with explicit control over state, branching, and human-in-the-loop steps.
Good for: Engineering teams building multi-step agents, Enterprise platform teams, Workflows needing human-in-the-loop control
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CrewAI
Agent DevelopmentA framework for orchestrating role-based multi-agent teams, where specialized agents collaborate on a task under a defined process.
Good for: Teams prototyping multi-agent workflows, Content and research automation, Engineering teams exploring agent collaboration
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Haystack
Agent DevelopmentAn open-source framework from deepset for building production LLM applications — RAG, search, and agents — built around composable pipelines.
Good for: Teams building production RAG and search, Engineering orgs that want inspectable pipelines, Enterprises evaluating managed LLM platforms
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LlamaIndex
Agent DevelopmentA data framework for connecting LLMs to private and enterprise data — ingestion, indexing, retrieval, and agent workflows over your own content.
Good for: Teams building RAG over internal data, Engineering orgs standardizing ingestion and retrieval, Enterprises with large, messy document sets
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Microsoft AutoGen
Agent DevelopmentAn open-source framework from Microsoft Research for building multi-agent applications, where agents converse to solve tasks together.
Good for: Engineering teams prototyping multi-agent systems, Research and innovation groups, Teams already in the Microsoft ecosystem
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OpenAI AgentKit
Agent DevelopmentOpenAI first-party agent toolkit — a visual Agent Builder, embeddable ChatKit UI, a connector registry, and evals, billed at plain API rates.
Good for: Product teams embedding agents into their own software, Engineering teams already building on the OpenAI API, Startups that want agent scaffolding without a platform fee...
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Semantic Kernel
Agent DevelopmentAn open-source SDK from Microsoft for integrating LLMs into applications, with a focus on enterprise-grade orchestration in C#, Python, and Java.
Good for: .NET and Java enterprise development teams, Orgs embedding AI into existing applications, Microsoft-ecosystem shops
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Frequently asked
- What are the best ai agent development tools?
- We track 7 Agent Development tools, 7 of which have a free or freemium tier you can evaluate without a sales call. Our picks are LangGraph, CrewAI and Haystack. Each entry below lists real pricing, what it is genuinely good at, and the limitations that only show up after you buy.
- Are there free Agent Development tools?
- Yes — 7 of the 7 tools we track in this category offer a free or freemium tier: LangGraph, CrewAI, Haystack, LlamaIndex, Microsoft AutoGen, OpenAI AgentKit, and others. Free tiers vary widely in usefulness, so check the individual entry for what the tier actually includes.
- How much do Agent Development tools cost?
- Pricing varies by model — per seat, per action, per credit, and per outcome are all common in this category. As one reference point, LangGraph: Open-source framework, free to use. Paid tiers apply to the surrounding LangSmith platform, not the framework itself.
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