OpenAI launches Decisions API for real-time finite-choice answers

At DevDay 2026, OpenAI introduced the Decisions API, which focuses Luna's intelligence on a specific set of user-defined questions with finite pre-defined answers so developers can classify content, route requests, or choose an agent's next action in near real time.

A chat reply can use any words. A live product needs one choice from a list the developer already wrote, so the next step is something software can route on. The Decisions API is OpenAI offering that closed pick as its own tool.

On Tuesday, 29 September 2026, OpenAI’s DevDay 2026 recap listed the Decisions API among new developer tools. The recap is dated September 29, 2026. An API is a door a developer’s own program can use. The program sends a question. OpenAI’s service sends an answer back. Those lines are on the recap.

OpenAI says the Decisions API is for decision-making in real time. Real time, here, means the answer is meant to arrive while a product is still in the middle of a task, not as a long essay afterward. The method, OpenAI says, is to focus Luna on a specific set of questions the developer writes, each with a finite list of answers written in advance. Finite means the list ends. Luna picks from those answers. It does not write a new one. Luna is the model OpenAI names for this job. A model, here, is the system that reads the material and chooses. Those lines are OpenAI’s.

What the developer sends, and what comes back. The developer supplies context as text or as images. Context is the material the question is about, such as a message, a page, or a picture. OpenAI says the answers that come back can classify content, route a request, or choose an agent’s next action. Classify means sort the material into a bucket the developer already named. Route means send the request down one path instead of another. An agent, here, is software that takes the next step in a task, not only a chat reply. Those uses are OpenAI’s.

Who can call it. OpenAI says the Decisions API is available in limited preview today, with a broad release planned in the coming days. Limited preview means a smaller set of developers can use it now. A broad release is the wider opening. The coming days is the window OpenAI names. Those lines are OpenAI’s.

In plain terms, a developer writes the questions and the allowed answers. Luna reads text or images and picks from that list. The pick can sort content, send a request somewhere, or tell an agent what to do next. The tool is in limited preview. OpenAI says a wider release is planned in the coming days.

The picture is a desk graphic of that path. A navy card carries copper type. Four steps run across it: questions, Luna, finite answers, and act. It is a diagram of the Decisions API section on the recap. It is not a screenshot of a product screen.