JSON Schema Generator
Paste a JSON object and get a JSON Schema with inferred types, required fields, and nested support.
Already have a schema? Validate JSON against it →
Related Tools
Validate JSON data against a JSON Schema. Supports draft-07 and 2020-12 with detailed error reporting.
Generate TypeScript interfaces from JSON data. Handles nested objects, arrays, nullable fields.
Generate realistic fake data in JSON, CSV, SQL INSERT, or TypeScript. Custom schemas and presets.
How to Generate a JSON Schema from Sample Data
Writing a JSON Schema by hand is slow when you already have a representative payload. This JSON Schema generator infers types, nested objects, and arrays from the JSON you paste, then emits a draft you can tighten with required fields and additionalProperties.
Use the output as a starting point for API contracts, not as a finished spec. Generated schemas cannot know which fields are optional across all responses unless you feed multiple examples. Pair it with the JSON Schema validator to check new payloads against the schema you just created.
Tips
- Paste a real API response rather than a hand-written happy-path object.
- Turn on “required for all keys” only if every field is always present.
- Review inferred types — a field that is sometimes null should be a union, not a single type.