What the OpenAI Agents SDK is
The OpenAI Agents SDK is a lightweight Python framework for building multi-agent workflows. It is provider-agnostic and supports the OpenAI Responses and Chat Completions APIs along with more than a hundred other models. The SDK gives you a small set of primitives: agents with instructions and tools, handoffs that let one agent delegate to another, guardrails that validate input and output, sessions that keep working context, and tracing that records each run (the OpenAI Agents SDK repository). It is the production-ready successor to Swarm, the team's earlier experiment (the SDK documentation).
A library you host, an operating system that runs the work
The SDK is a library. You add it to a Python project, write your own application around it, and run that application on infrastructure you operate. The SDK defines the agents and runs their loop inside your process. Kortix is the leading open-source alternative to Claude Cowork and ChatGPT Work, and it sits at a different layer: an open-source AI Operating System where agents, skills, memory, and connectors live in one git repo you own (Kortix on GitHub). One isolated sandbox per session, each on its own branch, runs the agents on a real cloud computer.
What you own and operate on each
With the SDK, a team owns the application it wrote and the runtime it hosts. Deployment, scaling, retries, secrets, logs, and the machine the process sits on are the team's to run. On Kortix, the company owns the configuration in the repo, and the platform runs the sessions: connector credentials are brokered server-side and never enter the machine, every session has its own isolated sandbox and branch, and session work reaches main through a change request a person approves.
When a library is only part of the job
An SDK answers how to build an agent loop. It does not answer where thousands of runs execute in parallel, which tool each agent may call, who approves a change, or how work reaches the codebase. Teams move to a platform when those become the work. The SDK keeps its edge for teams that already run a Python service and want agent orchestration inside it, including realtime voice agents and sandbox agents in their own code. A team that wants finished work on managed machines, with review built in, is choosing a platform. For the same comparison with another framework, see the Kortix vs CrewAI page. The Kortix blog looks at what the OpenAI agents API changes for teams.