The first sample is always optimistic
The payload you used to generate the Schema will usually pass. Acceptance means a second response, an error state, or a missing-field case.
JSON Tools for AI Developers · Runs locally
Natural language generation · Schema · Zod · OpenAPI · Function Calling · MCP · 30+ tools
A Schema generated from one sample is usually optimistic. You must press a second real response against it before you ship.
Paste the instance on the left, the Schema in the middle, click Validate. Missing required fields and wrong types show up in the report.
Common type, required, and properties are covered. Recheck obscure Draft keywords against the spec.
Validation runs locally. Production data does not need a third-party validator.
The payload you used to generate the Schema will usually pass. Acceptance means a second response, an error state, or a missing-field case.
Fix required and types first. Don't pile on anyOf and soften the Schema — a soft Schema stops constraining.
Format only checks whether the text is valid JSON. This page checks whether the instance matches a Schema.
The second payload added a field, dropped a required one, or turned a number into a string. That is what acceptance is for.
Common formats get a basic check. They do not replace backend validation.
No.
Errors try to include the field path. Read the path first, then the expected type.
Common combinations run. Trust especially complex ones only after you compare with a spec implementation.
If the Schema has items, each item is checked. Without items, the constraint is weak.
Yes: generate → human edit → validate a second payload → then export Zod / OpenAPI.