GUIDE · UPDATED OCTOBER 7, 2026
The OpenAI Decisions API
At DevDay on September 29, 2026, OpenAI announced a Decisions API built on a specialised version of GPT-6 Luna. Instead of generating text, it answers questions that have a finite set of developer-defined answers, from text or image context, and returns the chosen answer. OpenAI positions it for classifying content, routing requests and choosing an agent's next action, with answers in a fraction of a second.
Availability and pricing
After a limited preview, OpenAI opened the Decisions API to all API accounts in public beta on October 6, 2026, and expects general availability within weeks. The endpoint is POST /v1/decisions and gpt-6-luna is the only model. It bills input tokens only, at $0.10 per million; output and cache tokens are free.
Request format
A request has an input (text, or user messages with text and inline base64 images) and a questions array. Each question has a type: predicate returns the probability that a condition is true, choice returns one of your values with a probability for each, and score rates the input against ordered levels and returns a probability-weighted score. A question can come back as a refusal while the others are still answered.
Using it through this site
Decisions API (decisionsapi.pro) is an independent service that runs every request on the official OpenAI Decisions API. It adds a playground, free credits to start, self-serve keys, https image URLs and a simpler question format; the same endpoint also accepts OpenAI's own request body. See the OpenAI request format.
| OpenAI Decisions API | This Decisions API | |
|---|---|---|
| Status | Public beta | Live, runs on the OpenAI endpoint |
| Model | GPT-6 Luna | GPT-6 Luna |
| Input | Text and inline base64 images | Text, JSON, base64 images and https image URLs |
| Output | Typed answers with probabilities | The same answers, in either response format |
| Access | OpenAI API account, pay per token | Free credits, then token plans |
Decisions API (decisionsapi.pro) is not affiliated with or endorsed by OpenAI. OpenAI and GPT are trademarks of OpenAI. Details about the OpenAI product are from its public documentation as of October 7, 2026 and may change.