---
title: "How strict is OpenAI Structured Outputs with optional JSON fields?"  
description: "How strict is OpenAI Structured Outputs with optional JSON fields?"  
author: "Natalia Volkova"  
published: 2026-10-26  
updated: 2026-10-26  
canonical: https://www.mindstick.com/forum/162944/how-strict-is-openai-structured-outputs-with-optional-json-fields  
category: "OpenAI API"  
tags: ["OpenAI API", "Structured Outputs", "JSON schema"]  
reading_time: 1 minute  

---

# How strict is OpenAI Structured Outputs with optional JSON fields?

I’m using Structured Outputs to return records where some fields only apply in certain cases. What’s the best way to represent **[optional JSON fields](https://answers.mindstick.com/qa/117454/how-dependable-is-gpts-json-output-when-a-schema-has-optional-fields)** in a strict schema, especially when a field should be omitted in one case but set to `null` in another?

I’d also like to know where the API’s schema validation stops and application-level checks should begin. If you’ve handled conditional fields in a real integration, what schema shape worked reliably for you?


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Original Source: https://www.mindstick.com/forum/162944/how-strict-is-openai-structured-outputs-with-optional-json-fields

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