The JSON is valid but validation still fails

That means the syntax is fine but the data does not match the schema. Check required fields, property types, array item definitions, and enum or format constraints.

The generated schema is too strict or too loose

That's common with sample-based generation. Review required fields, nullable values, unions, and empty arrays before treating the schema as authoritative.

Why does schema draft matter here?

Different JSON Schema drafts support different keywords and interpretation details. This tool uses Draft 2020-12, so make sure your downstream tooling accepts that dialect.

An empty array produced a vague item schema

That's expected. A generator cannot infer array item structure from `[]`. Use a representative non-empty sample if you want better output.

Can generated schemas detect every optional field or union correctly?

No. Generation only sees the examples you provide. Fields that are sometimes absent, nullable, or polymorphic often need manual refinement.

Is my JSON uploaded anywhere?

No. Toolzy.dev runs validation and generation in the browser, so your JSON and schema stay local to your machine.

JSON Schema Validator / Generator

Validate JSON against a schema or generate a starter schema from a JSON sample, entirely in your browser.

Draft 2020-12

JSON input

Ctrl/Cmd+Enter

JSON Schema

Include $schema for the Draft 2020-12 schema identifier.

Explicit draft

Validation and generated examples use JSON Schema Draft 2020-12, so the target dialect stays visible instead of implicit.

Sample-based only

Generated schemas reflect only the sample JSON you provide. Missing keys, alternate shapes, and business rules are not inferred.

Human review still needed

Formats, enums, nullable behavior, and additionalProperties rules often need tightening after generation.