Structured Output

Overview

LLMs love to ramble. When you need JSON, you get JSON wrapped in markdown. When you need a list, you get a paragraph. Structured output forces the model to return exactly the schema you define — validated, typed, and ready to use in code without parsing gymnastics.

When to Use

• Extracting structured data from unstructured text (invoices, emails, articles)
• Building API responses powered by LLMs that must match a schema
• Creating reliable data pipelines where LLM output feeds into databases
• Generating configuration files, test cases, or code from natural language
• Any time you need JSON from an LLM, not prose

Instructions

Strategy 1: OpenAI Structured Outputs (Native)

OpenAI's response_format with JSON Schema guarantees valid JSON matching your schema. The model literally cannot produce non-conforming output.