📋 JSON Schema Generator
Generate JSON Schema from JSON data. Auto-detects types, arrays, and required fields.
📋 When to Use the JSON Schema Generator
The JSON Schema Generator is essential when you need to define a structural contract for your JSON data — whether you're documenting an API, setting up validation rules for incoming payloads, or bootstrapping an OpenAPI specification. Use it when designing new endpoints, verifying response formats during development, or converting sample data into a reusable type definition. Everything processes in your browser for maximum privacy.
⚙️ How the JSON Schema Generator Works
The JSON Schema Generator analyzes your JSON data using a recursive type-inference algorithm that runs entirely in your browser. When you paste a sample JSON object, JavaScript parses the input into a type tree, detects integer vs number, array item types, nested object structures, and automatically collects required field names. The algorithm walks every branch of your JSON to produce a complete draft-07 compatible schema. Everything stays on your device — your data is never uploaded to any server.
How to Use the JSON Schema Generator
- Paste your JSON data — enter a sample JSON object in the text area. The tool comes pre-filled with an example containing strings, numbers, arrays, and nested objects.
- Click Generate Schema — the tool analyzes your JSON structure and produces a JSON Schema (draft-07) that describes the types, required fields, and structure.
- Review the schema — check that all fields are detected correctly. Strings, numbers, booleans, arrays, and nested objects are all auto-detected with appropriate types.
- Copy and use — copy the generated schema for API documentation, validation, or OpenAPI specs. The schema is formatted and ready to use.
Frequently Asked Questions
What is JSON Schema used for?
JSON Schema provides a contract for what JSON data should look like — defining required fields, types, formats, and constraints. It's used for API validation, generating documentation, auto-completing IDEs, and ensuring data quality across systems.
How does the generator detect types?
The tool uses JavaScript's typeof operator plus Array.isArray() for type detection. Numbers become "number", strings become "string", booleans become "boolean", objects become nested schemas, and arrays auto-detect their item types from the first element.
Can I generate a schema from incomplete sample data?
Yes, but the schema will only include fields present in your sample. For a complete schema, provide a sample with all possible fields, including edge cases (null values, empty arrays, etc.). The generator marks all detected fields as required by default.
What JSON Schema version does this produce?
The generator produces JSON Schema draft-07 compatible output using $schema, type, properties, required, and items keywords. It's compatible with most validators including Ajv, jsonschema (Python), and OpenAPI 3.x.