📋

JSON Schema Generator

Paste JSON and instantly generate a JSON Schema with types, required fields, and nested object support.

Schema Title (optional)

Mark all fields requiredAllow additional properties

JSON Input

Generated JSON Schema

About JSON Schema Generator

Free online JSON Schema generator that creates a valid JSON Schema from any JSON data. Paste your JSON input and get a complete schema with type inference, nested object and array support, and optional required field annotations. Configure options like marking all fields as required, allowing additional properties, and adding a schema title. Supports complex structures including nested objects, arrays of objects, mixed-type arrays, integers vs. numbers, and null values. Uses the JSON Schema 2020-12 draft. 100% browser-based, no signup required.

Frequently Asked Questions

What is JSON Schema?▾

JSON Schema is a vocabulary for annotating and validating JSON documents. It defines the structure, types, and constraints of JSON data — like a blueprint for your API payloads, config files, or database records. Validators use schemas to check whether incoming data matches the expected format.

Which JSON Schema draft does this use?▾

This tool generates schemas using the JSON Schema 2020-12 draft (the latest stable version). The $schema keyword in the output confirms the draft version. The generated schemas are compatible with all major validators.

Does it handle nested objects and arrays?▾

Yes. The generator recursively processes deeply nested objects, arrays of objects, arrays of primitives, and mixed-type arrays. For mixed-type arrays, it uses the oneOf keyword to represent multiple possible item schemas.

What is the 'required' option?▾

When 'Mark all fields required' is checked, every property in every object is added to the required array. This means the validated JSON must include all those fields. Uncheck it if fields are optional in your data.

What does 'additional properties' mean?▾

When 'Allow additional properties' is unchecked, the schema includes additionalProperties: false, which means the validated JSON cannot contain any fields not listed in the properties object. This enforces strict structure validation.

Is this tool free?▾

Yes, completely free with no signup required. All processing happens in your browser — your JSON data is never sent to any server.