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OpenAI Agents SDK alternatives (2026)

OpenAI Agents SDK: MIT OpenAI agent workflow SDK. Build multi-agent loops; API spend is separate.

Its Catch: Vs openai-codex-cli (terminal coding agent), Vercel AI SDK (app AI primitives), and Microsoft Agent Framework: this is the workflow SDK, not the Codex CLI seat.

Below: 8 free or free-tier tools from the same category (agent frameworks and SDKs), free and open source first, then the closest match by shared tags. Each keeps its own Catch.

  1. 1.tRPC-Agent-GoApache-2.0 Go production agent framework — GraphAgent, MCP, A2A

    Free / OSS · Apache-2.0 · 1.9k GitHub stars

    VerdictApache-2.0 Go agent framework when GraphAgent + MCP/A2A belong inside Go services — skip if your team is Python-first and does not want another runtime.

    CatchGo-native stack with tRPC-ecosystem gravity — not a drop-in for Python LangGraph/Crew shops. Not a hosted product: you build and run the service. Pick it when Go is already the runtime, not as a reason to leave a working Python agent stack.

  2. 2.Microsoft Agent FrameworkMIT successor to AutoGen + Semantic Kernel — Python and .NET

    Free / OSS · OSS/MIT · 14.2k GitHub stars

    VerdictMIT Microsoft agent SDK. Prefer over AutoGen for new builds; watch Azure meters in prod.

    CatchVs AG2 (community AutoGen fork), LangGraph (graph orchestration), and Google ADK: MAF is Microsoft’s enterprise-shaped multi-agent SDK, not a coding seat. Foundry hosted agents and Azure model meters are paid paths — OSS framework still runs with BYO providers. AutoGen is maintenance-only; start new projects here, not there.

  3. 3.Strands AgentsApache-2.0 model-driven agent SDK from AWS — Python and TypeScript

    Free / OSS · Apache-2.0 · 8.9k GitHub stars

    VerdictApache-2.0 AWS agent harness. Model-driven + MCP; Bedrock optional, not mandatory.

    CatchVs Agno / OpenAI Agents SDK / Microsoft Agent Framework: Strands is AWS-born harness with Bedrock gravity, not a coding CLI and not a React copilot UI. Bedrock/AgentCore paths meter when you leave local/BYO. Bring your own model spend either way.

  4. 4.GriptapeApache-2.0 Python agents, pipelines, RAG — MCP tools too

    Free / OSS · Apache-2.0 · 2.6k GitHub stars

    VerdictApache-2.0 Python agent/RAG framework. MCP as tools; Cloud free tier is metered, not forever.

    CatchVs LangChain/LangGraph and CrewAI: Griptape is a structured Python agent/RAG framework, not a coding CLI. Cloud Developer free tier needs a payment method on file and meters after small included quotas — pitch the OSS framework first, not Cloud as free forever.

  5. 5.AgentScopeApache-2.0 agent framework for capable LLMs

    Free / OSS · Apache-2.0 · 33.5k GitHub stars

    VerdictA serious framework to evaluate next to LangGraph and similar tools.

    CatchIt gained about 232 stars a week since January 2024, backed by a large team and steady releases. Much of the community is Chinese-speaking. Version 2.0 changed the abstractions, so older examples may not apply.

  6. 6.BeeAI FrameworkApache-2.0 production agents in Python and TypeScript — MCP + A2A

    Free / OSS · Apache-2.0 · 3.4k GitHub stars

    VerdictApache-2.0 dual-language agent framework. MCP/A2A serve built in; you own ops and models.

    CatchVs Agno / VoltAgent / Google ADK (agent kits) and mcp-use / FastMCP (MCP server kits): BeeAI is dual-language agent framework + protocol serve, not a coding CLI and not a managed tool catalog. IBM open-source notice says community maintenance posture — treat it as OSS you own, not an IBM product SLA. A2A server is Python-first today.

  7. 7.CopilotKitMIT agent-native UI layer — React copilots, AG-UI, MCP

    Free / OSS · Freemium · 38.1k GitHub stars

    VerdictMIT agent UI layer. Self-host free; Cloud Developer free forever is real but capped.

    CatchVs Vercel AI SDK (primitives) and Mastra/LangGraph (backend agent runtimes): CopilotKit is the user-facing agent UI/protocol layer, not the orchestration brain. Pro/Team Cloud and VPC are paid when you outgrow Developer free forever. Self-host keeps the MIT path.

  8. 8.aclifAgent CLI framework — one grammar across SaaS providers

    Free / OSS · OSS/MIT · 20 GitHub stars

    VerdictMIT agent CLI framework. Use when agents should run one self-describing CLI instead of a pile of one-off tools.

    CatchVs MCP servers (protocol tools) and mcp2cli: aclif is an agent-native CLI framework, not an MCP server and not a thin wrapper generator alone. Early stars; you still implement/provider-wire the SaaS surfaces you need, and enterprise IdP reality sits outside the framework.

FAQ

What are the best free alternatives to OpenAI Agents SDK?
tRPC-Agent-Go, Microsoft Agent Framework, Strands Agents, Griptape, AgentScope. All are reviewed on Stack Gems in the same category (agent frameworks and SDKs); 8 free or open source.
What is the catch with OpenAI Agents SDK?
Vs openai-codex-cli (terminal coding agent), Vercel AI SDK (app AI primitives), and Microsoft Agent Framework: this is the workflow SDK, not the Codex CLI seat.
Is there an open-source alternative to OpenAI Agents SDK?
Yes: tRPC-Agent-Go (Apache-2.0), Microsoft Agent Framework (OSS/MIT), Strands Agents (Apache-2.0), Griptape (Apache-2.0).

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