Schema Preflight

STRICT JSON SCHEMA WORKBENCH

Check a JSON Schema before strict mode rejects it.

Paste a schema for OpenAI Structured Outputs and get browser-local checks for required fields, additionalProperties: false, root shape, nesting limits, and risky JSON Schema keywords.

root objectrequired parityclosed objects10-depth limit
Current scan
Strict-mode blockers found
1 findings - no upload

Preflight report

critical
CRITICAL / STATIC CHECKStrict-mode blockers found

1 blocker should be fixed before retrying.

Objects1
Properties2
Depth2
Rule set2026 docs
Set additionalProperties to false

Every object schema checked by strict Structured Outputs should explicitly set additionalProperties:false.

$.additionalProperties

Scope

Schema Preflight is a static browser check for the OpenAI Structured Outputs JSON Schema subset. It does not call the OpenAI API, validate model quality, or upload pasted schemas.

Non-affiliation

This independent tool is not affiliated with OpenAI. Always confirm critical production schemas against the current official documentation and the model or SDK you deploy.