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Open-Source AI Agent Frameworks

Open-source frameworks for building AI agents on code you can read, fork and self-host: from the largest ecosystems to the newest TypeScript-native entrant.

12 of the 14 agent frameworks in our index carry a clean, unrestricted open-source license on the code you would actually run. No source-available carve-out. No separate commercial license required to get the controls a production team needs while self-hosting. A framework is not a product you sign into; it is code that lands in your own repository, so the license attached to it matters more here than it does for a hosted agent.

Two of the 14 do not clear that bar, and both are open at the core. Mastra's framework is Apache-2.0 and free to self-host, but the RBAC, SSO and IAM controls a production team needs sit behind a separate Enterprise Self-Hosted tier, billed as a flat annual fee on top of the open code. Claude Agent SDK's Python and TypeScript wrapper packages carry an MIT license, but Anthropic's own docs state that using the SDK as a whole is governed by its commercial Terms of Service, so the license on the wrapper does not cover what you are actually agreeing to when you run it.

This is not the same list as our [open-source AI agent tools collection](/collections/open-source-ai-agent-tools/), which spans coding agents, voice agents and agent platforms too, not just the tools you build an agent with (every entry here also appears there). It is also not the same as our [ranking of all 14 frameworks](/best-ai-agent-frameworks/), which scores the full set on capability and includes Mastra and Claude Agent SDK alongside the 12 open ones here.

Among these 12: LangChain remains the largest and most integration-heavy framework in the group; Microsoft ships two that clear this bar, AutoGen and its newer successor, Agent Framework; and AgentsKit is the newest and least proven, four months old with an MIT core and its hosted layer, AgentsKit OS, still enterprise-only early access. Every one of them lets you point the framework at any model provider you choose and keep running if the vendor ever disappears, a guarantee a closed SDK cannot make.

Why this collection

A framework earns a place here only if it belongs to this site's frameworks category and 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 and no separate commercial license gating the controls a production deployment needs. This is the same bar our open-source AI agent tools collection applies, narrowed to one category. Verified against each framework's own listing research (license type, pricing tiers and FAQ text), not a vendor's marketing claim of "open source."

The full ranking method →

12 agents in this collection