Best by task · Agent building
Best AI agent tools for building agents
Short answer: If you are looking for AI agent tools, our current #1 for building agents is Claude Code, with the OpenAI Agents SDK second and LangGraph third. These are editorial picks, and most were smoke-tested on 2026-10-25 without vendor models. LangGraph and FastMCP ran with no LLM at all.
- 33tools ranked
20 Tested · 13 Reported
- people building their own agentswho it is for
- Oct 26, 2026last updated
Building your own agent means picking tools for tool-calling, memory, sandboxing and deployment. We track the releases that matter for that.
Last updated . Rankings are editorial; paid placements never affect them.
- 2OpenAI Agents SDKTested (smoke test)
- 1Claude CodeTested (smoke test)
- 3LangGraphTested (smoke test)
Kinds of AI agent tools
- Frameworks and SDKs for writing agents in code: LangGraph, CrewAI, OpenAI Agents SDK, Google ADK and Mastra.
- Tool servers that let agents reach other systems: FastMCP builds servers for the Model Context Protocol. See what is an MCP server.
- Workflow automation: n8n.
- Coding agents used as a base for agent workflows: Claude Code.
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Our ranked list
Claude Code
Plugins, skills, hooks and an Agent SDK are referenced in the changelog, which makes it a base for building your own agent workflows.
Verdict: Update now if you use the sandbox or run Claude Code on a cloud provider; skip if you wanted flashy new features, this is a hardening release.
OpenAI Agents SDK
MIT-licensed framework with MCP, sessions, tracing and realtime voice examples.
Verdict: Pick it if you want a small, official framework for multi-agent flows on the OpenAI API; the update is incremental.
LangGraph
MIT-licensed graph framework for stateful agents; the latest release is a patch.
Verdict: A dependable foundation for stateful agents; this release is a routine fix, so only update if the RemoteGraph or recursion fixes affect you.
Google ADK
Apache-2.0 toolkit with evaluation, live audio and new MongoDB services.
Verdict: Update with care: a big, useful release for Gemini users, but it includes a telemetry default change.
CrewAI
MIT framework with crew-style orchestration and a new eval command.
Verdict: Reasonable if you like the crew-of-agents mental model; the memory and tool-loop fixes in this release are worth taking.
Mastra
TypeScript-first framework with Studio, observability and MCP support.
Verdict: A strong TypeScript option if you are building agents in a Node stack; read the breaking-change note on sessions before upgrading.
FastMCP
A widely used Python library for MCP servers; the October releases are security-focused.
Verdict: If you run FastMCP servers, upgrade and read the security notices; the OAuth issuer step is not automatic.
n8n
Visual workflows plus native AI agents, with an agent builder and budget tracking.
Verdict: Great fit for small teams that want to wire apps and AI together without code; the license is fair-code, not open source.
Langflow
Low-code visual builder for agents, RAG and MCP servers.
Verdict: MIT-licensed visual builder for AI agents and MCP servers with a very large GitHub following.
Botpress
Agent platform for customer support with per-conversation pricing.
Verdict: Customer-support AI agent platform with a free plan and conversation-based paid plans.
Gumloop
Multiplayer agent builder with credit pricing.
Verdict: Agent builder for teams; plans start at $37 per month with 20k included credits.
Lindy
No-code AI employee builder with credit-based plans.
Verdict: AI 'employee' builder that connects to your tools; Free plan with $50 in credits that last 7 days, then credit-based plans.
Microsoft Copilot Studio
Microsoft's low-code platform for custom agents.
Verdict: Microsoft's platform for creating and managing custom agents, workflows and apps with no code.
Pydantic AI
Type-safe Python agent framework from the Pydantic team.
Verdict: Python agent framework built on Pydantic types, covering agents, realtime voice, image generation and embeddings.
Relevance AI
Specialist agents for sales, support and marketing.
Verdict: Platform for specialist AI agents for sales, customer success, marketing and HR, with an embedded deployment team.
Voiceflow
Enterprise chat and voice agent platform.
Verdict: Platform for chat and voice AI agents for customer experience teams.
Vercel AI SDK
TypeScript toolkit for LLM apps, streaming UIs and agents.
Verdict: Vercel's TypeScript SDK that gives one API across many model providers, with streaming and agent helpers.
Agno
Python agent framework and self-hosted agent platform.
Verdict: Open-source agent framework that now sells a self-driving agent platform you run in your own cloud.
Composio
Tool and auth layer connecting agents to 1,500+ apps.
Verdict: Managed tool-calling and authentication for agents across 1,500+ apps, with a free tier of 100,000 tool calls a month.
Dify
Visual LLM app and agent builder, self-hostable under a modified Apache license.
Verdict: Open-source platform for building LLM apps and agent workflows with a visual canvas; licensed under a modified Apache 2.0 with extra conditions.
OpenHands
Automations and SDK for building engineering agents.
Verdict: Open-source AI coding agent platform you can start locally, automate with workflows and run with any model.
LangChain
The most-starred Python and JS framework for LLM apps and agents.
Verdict: Open-source framework for building LLM applications and agents in Python and JavaScript, from the team behind LangGraph and LangSmith.
Haystack
Open-source Python framework for RAG and agent pipelines.
Verdict: Apache-2.0 Python framework for building search, RAG and agent pipelines, maintained by deepset.
Browser Use
Open-source library and cloud browsers for web agents.
Verdict: Open-source library that lets AI agents drive a browser, with a pay-as-you-go cloud browser starting at $0.02 an hour.
DSPy
MIT-licensed Python framework for composing and optimising LM programs.
Verdict: Worth a look if you want structured, testable LM pipelines; start with a plain Predict module before optimisers.
Semantic Kernel
Microsoft SDK for AI agents in .NET, Python and Java; successor is Microsoft Agent Framework.
Verdict: Microsoft's model-agnostic SDK for building AI agents; its README calls Microsoft Agent Framework the enterprise-ready successor.
Mem0
Memory layer API for agents and apps.
Verdict: Open-source and hosted memory layer that lets agents remember users across sessions, with a free tier and published request quotas.
LlamaIndex
Data framework for RAG and document agents.
Verdict: Open-source data framework for retrieval-augmented generation and document-centred agents, with a hosted document platform alongside.
Instructor
MIT-licensed structured-output library built on Pydantic.
Verdict: A small, light way to get typed output from a model; good first step before reaching for a full framework.
Flowise
Open-source visual LLM-flow builder; GitHub repository is archived.
Verdict: Open-source drag-and-drop builder for LLM flows and agents; GitHub marks the main repository as archived with its last push in Aug 2026.
smolagents
Minimal Hugging Face library for code-writing agents.
Verdict: Hugging Face's small Python library for agents that write and run code; the docs say the core logic fits in roughly a thousand lines.
Letta
Stateful agents with persistent memory.
Verdict: Platform and open-source framework for stateful agents that keep and improve memory across sessions.
AutoGen
Microsoft's multi-agent framework, now steering users to Microsoft Agent Framework.
Verdict: Microsoft's open-source multi-agent framework; its README now says the project is in maintenance mode and points to Microsoft Agent Framework.
Comparisons
For a head-to-head read of two frameworks, see LangGraph vs CrewAI. We have not run them against each other.
Side by side: what we recorded for the top 8
Every cell is read from the tool’s own pages on the date shown on its entry. “Not recorded” means we have not verified it, not that it does not exist.
| Tool | Pricing | Licence | Platforms | Evidence | Verified |
|---|---|---|---|---|---|
| Claude Code | Not verified, checked Oct 25, 2026 | Not recorded | Not recorded | Tested | |
| OpenAI Agents SDK | Not recorded | Not recorded | Not recorded | Tested | |
| LangGraph | Not recorded | Not recorded | Not recorded | Tested | |
| Google ADK | Not recorded | Not recorded | Not recorded | Tested | |
| CrewAI | Not recorded | Not recorded | Not recorded | Tested | |
| Mastra | Not recorded | Not recorded | Not recorded | Tested | |
| FastMCP | Not recorded | Not recorded | Not recorded | Tested | |
| n8n | Not recorded | Not recorded | Not recorded | Tested |
Who each pick suits
- Claude Code: Good for: Anyone relying on the Bash sandbox or permission rules (the 2.1.309 fixes close real gaps); Teams running Claude Code through Bedrock, Vertex or Foundry; Enterprise admins who want role-based control over cloud sessions and Remote Control. Skip it if: You are looking for new headline capabilities; these two releases are mostly fixes; You script claude ultrareview; check the new --trust-workspace requirement before updating CI.
- OpenAI Agents SDK: Good for: Python developers building agents on OpenAI models; Teams that want MCP tools plus approvals and sessions; Prototypers who want few abstractions. Skip it if: You need a TypeScript-first framework; You want a framework tied to no model vendor.
- LangGraph: Good for: Developers who want explicit control over agent state and flow; Teams running long-lived, resumable agents; People already in the LangChain ecosystem. Skip it if: You want the shortest path to a simple agent; You are looking for new features in this release.
- Google ADK: Good for: Python teams building on Gemini or Google Cloud; Developers who need live voice agents; Teams who want MongoDB-backed sessions and memory. Skip it if: You need identical telemetry across upgrades; defaults changed; You are not using Python.
- CrewAI: Good for: Developers who want role-based multi-agent flows; Teams that want a built-in eval command; Users who need vector search on Azure DocumentDB. Skip it if: You prefer an explicit graph model; You need a stable API with few releases; versions move quickly.
- Mastra: Good for: TypeScript and Next.js teams building agents; Teams that need observability and tracing out of the box; Developers experimenting with MCP events. Skip it if: You work in Python; You need a stable session API; this release changes it.
- FastMCP: Good for: Python developers building MCP servers or clients; Teams exposing internal tools to agents; Anyone running OAuth-protected MCP servers. Skip it if: You do not use MCP; You cannot update trust stores in your deployment environment.
- n8n: Good for: Small businesses automating lead capture and follow-up; Teams that want to self-host automations; Builders adding AI agents to existing workflows. Skip it if: You need a strictly open-source license (n8n is fair-code); You want a no-setup consumer app.
Compare the options
- AutoGen vs Agno: which should you use?
- AutoGen vs Semantic Kernel: which should you use?
- Composio vs Browser Use: which should you use?
- CrewAI vs AutoGen: which should you use?
- Flowise vs Langflow: which should you use?
- Gumloop vs Lindy: which should you use?
- LangChain vs LlamaIndex: which should you use?
- LangGraph vs CrewAI: which should you use?
- Letta vs Mem0: which should you use?
- LlamaIndex vs Haystack: which should you use?
- Mem0 vs LangChain: which should you use?
- Pydantic AI vs Mastra: which should you use?
- Semantic Kernel vs Google ADK: which should you use?
- smolagents vs Pydantic AI: which should you use?
- Vercel AI SDK vs OpenAI Agents SDK: which should you use?
- Voiceflow vs Botpress: which should you use?
Looking for something else? See all best-for categories, or the quick-answer tables.
Setup guides
- How to add an MCP server to Claude Code
- Best model for OpenCode, Cline and Claude Code: options by budget
- How to build an MCP server with FastMCP
- Is Claude Opus 5.5 free? Which plans include it
- GitHub MCP server: how to set it up
- Which coding agents can use GPT-6.1 Terra?
- How to run Claude Code with a local model
- Which Claude model should you use? Haiku 5.5, Sonnet 5.5, Opus 5.5 or Fable 5.1
FAQ
What are the best AI agent tools?
For building your own agents we rank Claude Code first, then the OpenAI Agents SDK and LangGraph. The ranking is editorial, and the ranked list on this page shows each tool's evidence label.
Which agent frameworks are open source?
LangGraph and CrewAI are MIT-licensed. See each tool page for its licence as read from its repository.
What is the best AI tool for agent building?
Our current top pick is Claude Code: Plugins, skills, hooks and an Agent SDK are referenced in the changelog, which makes it a base for building your own agent workflows. Rankings are editorial and paid placements never affect them.
How are the picks on this page chosen?
Ranks are editorial judgement made by Agentic Weekly when an entry is written or updated. They are not benchmark results, user ratings, popularity counts or paid positions. We rank only the 139 tools we track, not the whole market. "#1" means top of the tools we cover for that task, not best overall. The reason for each rank is the one-line blurb shown beside it. Typical reasons are how well the tool's own docs say it fits the task and how actively it is maintained according to its dated release notes. There is no numeric scoring formula, and we have not run quality head-to-head comparisons between ranked tools; our research studies measure install size, startup time and speed for some tools, and those numbers do not set ranks. Where a rank looks like a verdict on quality, it is our reading of official sources, not a measured result. The Tested label does not raise a rank. Tested means a small smoke test (install plus a short task, usually on a small local model), not a benchmark. Reported and Tested entries are ranked from the same kind of evidence. Payment cannot change a rank. Featured listings are labelled and are never used to order a list. Prices and plan details are shown only with a date and an official source. Where we could only find a third-party figure, or could not read the official page, the entry says so. Ranks can change when a release, price or doc changes. Each page shows when it was last verified.
How often is this list updated?
Every week, when new releases are added to the feed. Each entry shows its release date and when it was last verified.
How to cite this page
Agentic Weekly, "Best AI tools for building agents (updated weekly)", last updated 2026-10-26, https://theagenticweekly.com/best/agent-building
Keep the Reported or Tested label when you quote a verdict. Plain-text version: https://theagenticweekly.com/best/agent-building.md. More for AI assistants: /ai, /tools.json, /llms.txt.
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