Curated collection
Open Source AI Agent Tools
The 26 tools in our index with a clean, unrestricted OSI-style license (MIT, Apache-2.0, GPL-3.0-or-later or AGPLv3) — free to fork, self-host and run forever, no source-available caveats and no proprietary layer gating the part you would actually run.
On this page
We checked the license behind all 126 tools in our index and found 33 that call themselves open source in some form, but only 26 clear the bar of a clean, unrestricted license with no strings attached. This collection is those 26: the tools you can fork today, self-host forever, and keep running even if the vendor disappears, with nothing held back behind a separate commercial tier.
At a glance
- agents
- 26
- curated for this set
- Free to start
- 26 of 26
- a free or freemium entry tier
- Public API
- 22 of 26
- 2 more only on a paid tier
- Publish a price
- 26 of 26
- an anchor price on their own page
What this collection covers
The other seven "open" tools don't make this list, and that's deliberate: n8n and Dify both hedge their openness with a license condition their own docs tell you to check (fair-code, added-conditions Apache), Mastra and OpenHands are open at the core but gate their enterprise controls behind a separate paid license, Sim is open-source at the code level (29.4k GitHub stars) but sells self-hosting itself only on its Enterprise tier, and Warp and Claude Agent SDK each open-source only one half of the product: Warp's terminal client (AGPL-3.0/MIT) while its Oz cloud-agent platform stays closed, and the Agent SDK's two wrapper packages (MIT) while the Claude Code CLI binary they spawn as a subprocess is never published as source. Junie isn't part of that "hedged open" group either. It's simply closed-source, with no public repository at all. Real, legitimate business models, just not a "no caveats" self-hosting story. See our full license census for the complete breakdown, caveats included.
This list isn't the same set as our [self-hostable collection](/collections/ai-agent-tools-you-can-self-host/), even though the two overlap heavily. 24 of these 26 tools also appear there. Cartesia and Kilo Code are the two exceptions. Cartesia's Apache-2.0 Line SDK is unconditionally open but its voice runtime only ever runs on Cartesia's own infrastructure. Kilo Code was added to this collection on 2026-08-18, the same day it was published, and the self-hostable collection has not yet been re-read to include it. That collection also counts 13 tools that don't clear this one's bar: Mastra, Claude Agent SDK, n8n and Dify carry a license condition on an otherwise-open core, and Augment Code, Factory, CodeRabbit, Bland AI, Deepgram Voice Agent API, Windsurf, Warp, OpenHands and Junie are closed-source products that still sell a real self-hosted or on-prem path. If what you actually need is "can I run this myself," check that collection instead.
How these 26 agents were picked
A tool earns a place here only if its entire self-hostable codebase carries a clean, unrestricted OSI-style license (MIT, Apache-2.0, GPL-3.0-or-later, or AGPLv3) with no source-available carve-out, no fair-code condition, and no proprietary enterprise layer gating the part you'd actually run. Verified against each tool's own GitHub license file or our sourced listing research, not a vendor's marketing claim of "open source."
We distinguish an open core from the complete runnable product: a hosted control plane, closed runtime, source-available restriction, fair-code clause, or paid license for self-hosting excludes the listing even when part of its repository is public. Each refresh rechecks the license identifier, repository scope, self-hosting path and whether the licensed code is sufficient to operate the product independently of the vendor.
The 26 agents on this shelf

LangChain
Open source agent frameworks plus LangSmith, the platform for tracing, evaluating and deploying agents.
Agent frameworksFree, then $39/seat/monthAPIAutonomousClaudeVerified 14 days agoBest for Engineering teams building a bespoke, production-grade agent who want the largest integration ecosystem plus real stateful control.
The most widely adopted agent framework; MIT-licensed core, free to self-host with no vendor lock-in.

CrewAI
Open-source multi-agent framework with a managed platform for deploying and governing agent workflows.
Agent frameworksFreeAPIAutonomousClaudeVerified 3 days agoBest for Developers who want to stand up a role-based, collaborating multi-agent system quickly in Python, with a stable MIT-licensed core and a hosted build and runtime for production.
MIT-licensed multi-agent orchestration framework, reached a stable 1.0 general-availability release in October 2025.

AutoGen
Microsoft's open-source Python framework for building single- and multi-agent applications; now in maintenance mode.
Agent frameworksFreeAPIAutonomousClaudeVerified 14 days agoBest for Python or .NET developers and researchers exploring multi-agent orchestration who want a mature, free, self-hosted framework.
Microsoft's MIT-licensed multi-agent framework: free to self-host, pay only your own model provider.

Microsoft Agent Framework
Open-source SDK for AI agents and multi-agent workflows across .NET, Python and Go.
Agent frameworksFreeAPIAutonomousClaudeVerified 14 days agoBest for .NET or Python teams already invested in Azure or Microsoft Foundry who want one supported agent SDK, an optional managed hosting path, and a documented migration off AutoGen or Semantic Kernel.
Microsoft's MIT-licensed successor to AutoGen and Semantic Kernel: free to self-host across .NET, Python and Go, or an optional Azure-billed managed layer on top.

LlamaIndex
Open-source agent framework plus a credit-metered document parsing, extraction and indexing platform.
Agent frameworksFree, then $50/monthAPIClaudeEnterpriseVerified 14 days agoBest for Engineers building RAG-heavy or document-heavy agents who want an MIT-licensed OSS core with an optional managed parsing and extraction platform on top.
MIT-licensed core framework for building agents over your own data; the paid LlamaCloud parsing layer is optional.

LangGraph
Open-source orchestration framework and runtime for stateful, long-running LLM agents, from LangChain.
Agent frameworksFree, then $39/monthAPIAutonomousClaudeVerified 14 days agoBest for Engineering teams building production agents who need cyclical graphs, durable state and replayable runs
MIT-licensed agent runtime from the LangChain team, free to self-host; LangSmith and LangGraph Platform are optional hosted layers on top, not a gate on the library itself.

OpenAI Agents SDK (Python)
Open-source Python framework for building agents with tools, handoffs, guardrails, sandboxes and tracing.
Agent frameworksFreeAPIAutonomousFree tierVerified 14 days agoBest for Developers who want the fastest, lightest way to ship a straightforward agent (support triage, a tool-using assistant or a sandboxed coding agent) with tracing and guardrails included.
MIT-licensed and free to self-host: OpenAI's own lightweight SDK for building agentic workflows.

Pydantic AI
Typed Python agent framework: any model, any surface, with a harness for long-running coding and research agents.
Agent frameworksFreeAPIAutonomousClaudeVerified 14 days agoBest for Python teams building type-safe agents who also want realtime voice, image generation and embeddings in one SDK, with optional durable execution via Temporal, DBOS, Prefect or Restate.
MIT-licensed, type-safe Python framework from the team behind Pydantic: free to run anywhere.

Letta
Stateful agent harness, cloud and SDK for agents with persistent, git-versioned memory.
Agent frameworksFree, then $20/monthAPIAutonomousClaudeVerified 14 days agoBest for Developers and researchers who specifically need an agent whose memory, skills and identity genuinely persist and evolve across long-running sessions, rather than reset on every call.
Apache-2.0 licensed agent framework with persistent memory; self-host free or opt into managed Letta Cloud later.

Cline
Open-source coding agent for VS Code, JetBrains, the terminal and CI, running on whichever model you bring.
Coding agentsFree, then $9.99/monthAPIAutonomousClaudeVerified 5 days agoBest for Developers and teams who want a transparent, open-source, model-agnostic agent they fully control and pay for by usage, with optional flat-rate access to open-weight models.
Apache-2.0 licensed VS Code, JetBrains and CLI agent: only Enterprise SSO and support sit behind a paid tier.

Aider
Open-source terminal AI pair programmer that edits and commits code in your local git repo.
Coding agentsFreeClaudeFree tierGPTVerified 7 days agoBest for Developers who want free, model-agnostic AI pair programming in their terminal
Apache-2.0 licensed terminal coding agent, free forever: bring your own model API key or run a local model.

Codex CLI
OpenAI's terminal coding agent for inspecting, editing and running repository code from the shell.
Coding agentsFree, then $8/monthAPIAutonomousFree tierVerified 14 days agoBest for Developers who already pay for a ChatGPT plan and want a terminal-native agent with granular, inspectable sandbox/permission controls across CLI, desktop and IDE surfaces.
Apache-2.0 licensed CLI is fully open, even though the OpenAI models it calls are not.

OpenCode
Open source AI coding agent for the terminal, desktop, browser and IDE, running any model you connect.
Coding agentsFree, then $10/monthAPIAutonomousClaudeVerified 14 days agoBest for Developers who want a genuinely free, fully open-source coding agent that works with any model provider, including their own local Ollama models, without being locked into one vendor's terminal tool.
MIT-licensed terminal coding agent with 188,976 GitHub stars: one of the most active open-source projects in the category.

zot
Single-binary terminal coding agent harness in Go: five built-in tools, most providers, extensions in any language.
Coding agentsFreeAPIAutonomousClaudeVerified 14 days agoBest for Developers who want a fast, free, Go-native coding-agent harness with real session-branching control and are comfortable running fast-moving, self-described "beta forever" software from an independent maintainer.
MIT-licensed single Go binary, no signup or Docker required: bring your own API key or run local Ollama models.

Juggler
Visual workbench for AI coding agents: branching conversation trees, inspectable model transactions, local or remote.
Coding agentsFreeAutonomousClaudeFree tierVerified todayBest for Developers who want hands-on visibility into what an AI coding agent is doing to their codebase and accept early-stage, self-hosted, open-source software.
AGPLv3 for the main app, Apache-2.0 for its extension SDK: a stronger copyleft commitment than most rivals.

LiveKit Agents
Open-source Python and Node.js framework for voice AI agents, with LiveKit Cloud hosting, telephony and observability.
Voice agentsFree, then $50/monthAPIAutonomousClaudeVerified 14 days agoBest for Engineering teams that want to own their voice-agent stack end to end, self-hosted or on LiveKit Cloud, without being locked into one vendor's API.
Apache-2.0 licensed voice-agent framework: one of only two clean open-source picks in the voice-agents category, alongside the Apache-2.0 Line SDK that Cartesia ships.

GPT Researcher
Open-source autonomous research agent that writes cited long-form reports from web and local sources.
Research & data agentsFreeAPIAutonomousClaudeVerified todayBest for Developers and AI engineers who want a free, self-hosted research agent they can embed via Python, REST or MCP and run against their own LLM and search keys.
Apache-2.0 licensed: the only clean open-source pick in the research-agents category.

Zed
Rust code editor with an Agent Panel running Zed's own agent, ACP external agents, or terminal agent CLIs.
Coding agentsFree, then $10/monthClaudeEnterpriseFree tierVerified 14 days agoBest for Developers who want a fast, open-source editor and the freedom to run Claude Code, Codex, Gemini CLI or other vendors' own agents natively via the Agent Client Protocol Zed created, instead of being locked into one editor's built-in agent.
GPL-3.0-or-later core (Apache-2.0 for select components): the first full IDE in this collection, rather than a CLI tool or editor extension.

Google Agent Development Kit (ADK)
Open-source framework for building, evaluating and deploying AI agents in Python, TypeScript, Go, Java or Kotlin.
Agent frameworksFreeAPIAutonomousClaudeVerified yesterdayBest for Teams that want Google's own official, actively-developed agent SDK, especially polyglot teams (Python/Go/Java/TypeScript/Kotlin) or anyone building multi-agent systems that need to interoperate across vendors via the A2A protocol.
Apache-2.0 licensed across all four of its language SDKs (Python, Go, Java, TypeScript): Google's own official agent framework, free to self-host anywhere.

Botpress
AI agent platform with a visual studio, a code-first TypeScript ADK and a helpdesk, priced per conversation.
Agent platformsFree, then $189/monthAPIAutonomousClaudeVerified 14 days agoBest for Engineering-led teams building a multi-channel AI support agent who want an open-source, self-hostable core with an optional managed cloud layer.
MIT-licensed at the core with no license caveat, so it belongs on this list as squarely as any framework here; the managed cloud is an option alongside self-hosting rather than the only way to run it.

Cartesia
Real-time speech models and a managed runtime for production phone and web voice agents.
Voice agentsFree, then $5/monthAPIAutonomousClaudeVerified 14 days agoBest for Engineering teams that want an open-source voice-agent SDK with real LLM choice, built on speech models several rival platforms in this category already license as a component.
Line, its voice-agent SDK, is Apache-2.0 with no caveat: the second open-source entry in the voice-agents category alongside LiveKit Agents; the Sonic/Ink speech models it calls, and the Line runtime itself, stay proprietary and Cartesia-hosted.

Agno
Python SDK, open-source AgentOS runtime and hosted control plane for building and operating agents.
Agent frameworksFree, then $150/monthAPIAutonomousClaudeVerified 14 days agoBest for Python developers who want an Apache 2.0 SDK with memory, knowledge, learning, guardrails and a Control Plane they run inside their own cloud account, and who are comfortable running Docker or a cloud deploy template themselves.
Apache-2.0 licensed Python framework, formerly Phidata, with built-in memory, knowledge and multi-agent Teams; the paid AgentOS runtime is a separate BYOC product, not a gate on the framework itself.

AgentsKit.js
TypeScript foundation for AI agents: runtime, tools, memory, RAG, model adapters and headless chat UI bindings.
Agent frameworksFreeAPIAutonomousClaudeVerified 7 days agoBest for JS/TS developers who want an ownable, dependency-light agent toolkit
MIT-licensed TypeScript foundation for building agents: the Registry's ready-made agent factories are copied straight into your own codebase rather than pulled from a hosted runtime. A separate hosted product, AgentsKit OS, exists in enterprise-only early access with no self-serve signup, but the open-source core remains the only way most teams will run it.

OpenClaw
Self-hosted gateway that connects chat apps like WhatsApp, Telegram and Slack to AI agents on your own machine.
Agent platformsFreeAPIAutonomousClaudeVerified 14 days agoBest for Developers and self-hosters who already run their own infrastructure and want one personal AI agent that reaches WhatsApp, Telegram, Slack, Discord, Signal and iMessage instead of a separate app.
MIT-licensed personal AI agent that installs and runs on your own machine: the second agent platform in this collection with a clean, unrestricted license after Botpress, but with no managed cloud tier alongside it at all.

goose
Open-source local AI agent — desktop app, CLI and ACP server — running on the LLM provider you bring.
Coding agentsFreeAPIAutonomousClaudeVerified yesterdayBest for Devs who want an open source coding agent that reuses an existing Claude or ChatGPT plan
Apache-2.0 licensed and now stewarded by the Linux Foundation's Agentic AI Foundation: free to self-host as a desktop app, CLI or embeddable API, with no managed cloud tier and no enterprise carve-out on the code.

Kilo Code
Open source AI coding agent for VS Code, JetBrains, CLI and cloud, with 500+ models at provider rates.
Coding agentsFree, then $15/monthAPIAutonomousClaudeVerified 14 days agoMIT-licensed end to end and explicitly built to be self-hosted instead of relying on Kilo's own hosted Gateway: the extension, CLI and cloud-agent code all carry the same license, with no enterprise carve-out.
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