Letta
Open-source platform from the creators of MemGPT for stateful AI agents that keep long-term memory and learn over time. Use the Letta Code app (npm i -g @letta-ai/letta-code), the hosted API, or self-host the open-source server. Advanced: best for people comfortable with a terminal or APIs.
Research notes
How we research- Official site loadsChecked Oct 26, 2026: letta.com
- Pricing checked on the vendor siteSource: https://docs.letta.com/pricing
- Free / DIY pathUse the free plan with your own API keys, or self-host the open-source server (Apache-2.0)
Listed because it fits the Agent Tools category. Listings are free; sponsored placements, if any, are labeled and never change rankings.
Alternatives
OpenClaw
Agent ToolsOpen-source personal AI agent that runs on your machine and connects to chat apps.
Hermes Agent (Nous Research)
Agent ToolsOpen-source self-improving agent from Nous Research with skills and memory.
LangGraph
Agent ToolsFramework for building stateful, controllable multi-step agents.
CrewAI
Agent ToolsFramework/platform for role-based multi-agent 'crews'.
n8n
Agent ToolsVisual workflow automation with AI agent nodes; self-host or cloud.
OpenAI Agents SDK
Agent ToolsLightweight Python SDK for agents with tools, handoffs and guardrails.
Claude Code
Agent ToolsAnthropic's agentic coding tool for terminal and IDE.
LlamaIndex
Agent ToolsFramework for document agents and RAG over PDFs/specs.
Microsoft AutoGen
Agent ToolsMicrosoft's open-source multi-agent framework (being archived; successor is Microsoft Agent Framework).
Pydantic AI
Agent ToolsPython agent framework from the Pydantic team with typed outputs.
Google Agent Development Kit (ADK)
Agent ToolsGoogle's open-source framework for building and deploying agents.
Mastra
Agent ToolsTypeScript agent framework with hosted platform.
Haystack (deepset)
Agent ToolsOpen-source framework for RAG pipelines and agents.
Dify
Agent ToolsOpen-source visual builder for LLM apps and agent workflows.
Microsoft Semantic Kernel
Agent ToolsMicrosoft's open-source SDK for AI agents in C#, Python, Java.
Agno
Agent ToolsOpen-source Python SDK for building agents, teams and workflows (100+ toolkits, memory, MCP, A2A), plus the self-hosted AgentOS runtime and an optional hosted control plane.
MausBot
Agent ToolsOpen-source (Apache-2.0) desktop app for running a team of AI bots, each with its own job and model, plus tools, scheduled routines and approval settings. Pre-1.0 (v0.1.x).
Activepieces
Agent ToolsWorkflow automation and AI-agent builder, an n8n/Zapier alternative with a self-host option.
Agent-Native (Builder.io)
Agent ToolsOpen-source TypeScript framework for building AI agents that come with their own app UI; one action is exposed to the UI, agent, API, CLI and MCP. Bring your own LLM. Beta; developer-oriented.
goose
Agent ToolsFree, open-source general-purpose AI agent that runs on your machine as a desktop app (macOS, Linux, Windows), CLI or API. Use it for research, writing, workflows and data work, not just code; connects to 70+ MCP extensions and 15+ model providers, including local Ollama. Originally from Block; now part of the Agentic AI Foundation at the Linux Foundation.
Langflow
Agent ToolsLow-code visual builder for AI agents and chat-with-your-documents (RAG) apps: drag components together, customize with Python, and expose a flow as an API or MCP server. Works with major model providers and vector databases, including Ollama for local models.
Grok Bot
Agent ToolsAI teammates ("Bots") from SpaceXSI that work on their own persistent cloud computer with a browser, files and terminal, using app connectors, reusable skills and scheduled routines. We use it ourselves to run our research and site team.
smolagents
Agent ToolsHugging Face's small, open-source Python library for building AI agents that write and run code to get tasks done. Works with local models (Ollama, LM Studio) or hosted APIs. Advanced: needs some Python.
Firecrawl
Agent ToolsWeb search and scraping API that turns websites into clean, AI-ready text or JSON for agents, so an AI assistant can read supplier sites, bid boards or product pages. Open source and self-hostable.