What is a JSON Schema?

JSON Schema is a vocabulary for describing the structure and validation rules of JSON data. It defines what properties are allowed, their types, required fields, and constraints like min/max values or string patterns.

How do I generate a JSON Schema from sample data?

Paste a sample JSON document and click Generate. The tool analyzes the structure and types to produce a draft JSON Schema that validates documents with the same shape as your sample.

Which JSON Schema version is generated?

The tool generates schemas compatible with JSON Schema Draft 2020-12 (the latest draft), which is supported by most validation libraries including Ajv, jsonschema, and everit-json-schema.

Can I use the generated schema for API validation?

Yes. The generated schema can be used directly with schema validation libraries in any language, in OpenAPI/Swagger definitions, or with form validation tools to ensure incoming data matches the expected structure.

Can I use generated schemas for AI structured outputs?

Yes. Generated schemas are a strong starting point for OpenAI Structured Outputs, Anthropic tool input_schema objects, MCP inputSchema definitions, and any workflow where a model must return predictable JSON. You may still want to tighten additionalProperties, enums, and required fields before production use.

JSON-Schema-Generator

JSON Schema aus Beispiel-JSON generieren

JSON-Eingabe

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JSON-Schema-Ausgabe

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Build a JSON Schema from a real payload

Writing JSON Schema by hand is slow and easy to get wrong. Generating one from a sample document gives you a solid starting point — types inferred from values, required fields detected from presence, and nested objects expanded — that you can tighten with enums, formats, and constraints before shipping.

Use the generator when you need to

Bootstrap a contract for a new API

Take a sample response and generate a Draft 2020-12 schema you can refine with proper validation rules.

Validate AI structured output

Lift the schema from a known-good model response so downstream validation has something concrete to enforce.

Document the shape of a payload

Use the generated schema as living documentation of what your service produces or expects.

How to generate a JSON Schema

1
Paste a representative sample JSON document.
2
Click Generate to produce a Draft 2020-12 schema with inferred types and required fields.
3
Refine the schema with enums, patterns, and explicit required arrays before adopting it.

Keep going

Validate against the generated schema

Check real payloads against the schema you just generated.

Wrap for OpenAI or Anthropic

Adapt the schema for OpenAI Structured Outputs, Anthropic tools, or MCP definitions.

Generate TypeScript types

Pair runtime validation with compile-time types from the same sample.

Generate matching mock data

Produce fake records that satisfy the schema for tests and prototypes.

Common schema-generation workflows

Lock down an internal API contract

Generate the schema once, commit it to source control, and reject deviations in CI.

Constrain LLM tool calls

Use the generated schema to enforce that model output matches what your handler expects.

Migrate from no validation to schema validation

Quickly produce schemas for existing payloads and start enforcing them in stages.

Häufig gestellte Fragen

JSON Schema ist ein Vokabular, um Struktur und Validierungsregeln von JSON-Daten zu beschreiben. Es definiert, welche Properties erlaubt sind, welche Typen sie haben, welche Felder required sind und welche Constraints gelten (z. B. min/max oder String-Patterns).

Füge ein Beispiel-JSON ein und klicke auf Generate. Das Tool analysiert Struktur und Typen und erstellt daraus ein JSON-Schema-Template, das Dokumente mit derselben „Shape“ wie dein Sample validiert.

Das Tool erzeugt Schemas kompatibel zu JSON Schema Draft 2020-12 (aktueller Draft). Das wird von den meisten Validierungsbibliotheken unterstützt, u. a. Ajv, jsonschema und everit-json-schema.

Ja. Du kannst das Schema direkt mit Schema-Validatoren in jeder Sprache nutzen, in OpenAPI/Swagger-Definitionen einbinden oder für Formularvalidierung verwenden, damit eingehende Daten der erwarteten Struktur entsprechen.