Free JSON Schema Generator – Generate Schema from JSON
Paste any JSON and instantly get a JSON Schema definition. Perfect for documenting APIs, validating data structures, or starting a schema from scratch — runs in your browser, no data sent anywhere.
JSON Input
Generated Schema
What Is a JSON Schema Generator?
Ever had to write a JSON Schema by hand from scratch? It's tedious. This tool does it for you — paste in a sample JSON object and it instantly generates a schema that describes that structure: types, properties, required fields, and nested objects. The generated schema follows RFC 8259 JSON conventions and is compatible with tools like Ajv. Use it to jumpstart API documentation, validate data pipelines, or create schemas for OpenAPI specs.
This tool runs in your browser. Paste your JSON, and it generates a JSON Schema draft. Nothing is sent to a server.
How to Use This Tool
Paste Sample JSON
Paste JSON that represents the structure you want to describe. Use Sample or Upload if needed. The generator infers types from the values (string, number, boolean, array, object).
Review the Schema
The right panel shows the generated schema. It may include type, properties, required, and nested schemas for objects. You can edit it manually if needed.
Copy or Download
Use Copy or Download to get the schema. For validating JSON against a schema, use the JSON Validator or a library like Ajv.
JSON Schema Examples
Generate a schema from sample JSON. Telecom-themed example:
JSON input
Generated schema
When to Use a Generated Schema
Generated schemas are a starting point. They capture the structure of your sample data but may be too strict or too loose. You might need to add required arrays, adjust types, or add enum for allowed values. The JSON Schema docs explain the full vocabulary. For API documentation, tools like OpenAPI can reference JSON Schema.
Example: Generate a schema from a user object
JSON input:
{
"id": 1,
"name": "Alice",
"email": "[email protected]",
"age": 30,
"active": true
}Generated JSON Schema:
{
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "object",
"properties": {
"id": { "type": "integer" },
"name": { "type": "string" },
"email": { "type": "string" },
"age": { "type": "integer" },
"active": { "type": "boolean" }
}
}Frequently Asked Questions
How do I generate a JSON Schema from a JSON object?
Paste your JSON object into the left panel on this page. The tool automatically infers the schema — types, properties, and nested structures — and displays it on the right. No setup needed.
Can I use the generated schema to validate JSON?
This tool only generates schemas. To validate JSON against a schema, use the JSON Validator or a library like Ajv in your code.
What if my JSON has optional fields or multiple shapes?
The generator infers from the sample you provide. If your JSON can have multiple shapes (e.g. optional fields or union types), the schema might need manual edits. Use oneOf or anyOf for variants — the JSON Schema docs cover this well.
Is my data sent to a server?
No. Schema generation runs entirely in your browser. Your data is never uploaded or stored anywhere.
Can I use this to generate schemas for API responses?
Yes — that's one of the most common use cases. Paste a typical API response and the tool gives you a starting schema. You can then refine it and use it in OpenAPI/Swagger docs or for runtime validation.
Related Tools
Learn more at json-schema.org and JSON Schema learn. For validation in code, see Ajv. For JSON, see json.org, MDN, and RFC 8259. For API documentation, see OpenAPI.