JSON Mode

JSON Mode forces LLMs to output syntactically valid JSON, eliminating parsing errors in automated workflows.

JSON Mode ensures 100% parseable responses by constraining the model to follow a specific structural syntax. It solves the 'hallucinated text' problem (where models add conversational filler around data) by strictly outputting an object. Developers use it to build reliable pipelines for tools like LangChain or custom internal dashboards. When enabled via the API (setting response_format to { 'type': 'json_object' }), the model guarantees the output starts with a brace and follows standard RFC 8259 rules.

https://platform.openai.com/docs/guides/structured-outputs