Last year at DevDay, we introduced JSON mode—a useful building block for developers looking to build reliable applications with our models. While JSON mode improves model reliability for generating valid JSON outputs, it does not guarantee that the model's response will conform to a particular schema. Today we're introducing Structured Outputs in the API, a new feature designed to ensure model-generated outputs will exactly match JSON Schemas provided by developers.

Generating structured data from unstructured inputs is one of the core use cases for AI in today's applications. Developers use the OpenAI API to build powerful assistants that have the ability to fetch data and answer questions via function calling(opens in a new window), extract structured data for data entry, and build multi-step agentic workflows that allow LLMs to take actions. Developers have long been working around the limitations of LLMs in this area via open source tooling, prompting, and retrying requests repeatedly to ensure that model outputs match the formats needed to interoperate with their systems. Structured Outputs solves this problem by constraining OpenAI models to match developer-supplied schemas and by training our models to better understand complicated schemas.

On our evals of complex JSON schema following, our new model gpt-4o-2024-08-06 with Structured Outputs scores a perfect 100%. In comparison, gpt-4-0613 scores less than 40%.