Input (JSON)
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Output (JSON Schema)
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Most developers discover JSON Schema the hard way.
A third-party API starts sending malformed payloads. A frontend team submits data in the wrong shape. A config file gets edited manually and a required field goes missing. The bug reaches production.
JSON Schema is how you validate your data. And our free JSON Schema Generator is how you create it — without writing a single line of schema by hand. Paste a sample JSON object above and get a complete, valid JSON Schema in seconds.
JSON Schema is a vocabulary that lets you describe the structure, data types, and constraints of a JSON document. Think of it as a contract: it defines exactly what a valid JSON object looks like, so any JSON that doesn't match can be rejected before it causes problems downstream.
{
"id": 101,
"username": "alice_dev",
"email": "alice@example.com",
"age": 28,
"isActive": true,
"tags": ["admin", "editor"]
}{
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "object",
"required": ["id", "username", "email", "age", "isActive", "tags"],
"properties": {
"id": { "type": "integer", "description": "Unique identifier" },
"username": { "type": "string", "description": "User's username" },
"email": { "type": "string", "format": "email" },
"isActive": { "type": "boolean" },
"tags": {
"type": "array",
"items": { "type": "string" }
}
}
}That schema can now be used in any JSON Schema-compatible library across Python, JavaScript, Java, Go, Ruby, PHP, and dozens of other languages to validate every JSON document against those exact rules.
Every value is analyzed to determine if it's a `string`, `integer`, `number` (float), `boolean`, `array`, `object`, or `null`.
Recursive processing handles deep nesting, creating `properties` blocks for every level of your object hierarchy.
All fields present in the sample are initially marked `required`. You can easily adjust this in the output.
Strings matching emails, URIs, dates, or UUIDs get automatic `"format"` keywords for richer semantic validation.
Paste any JSON object — no matter how deeply nested — and get a complete Draft-07 JSON Schema in one click.
Real-world JSON is rarely flat. The generator handles arbitrary nesting depth with correct structure.
Analyzes arrays to determine if they contain uniform items or mixed types, setting `items` schema accordingly.
Strings like emails, dates, URIs get `"format"` keywords automatically for powerful validation.
The generated schema is fully editable. Add `minimum`, `pattern`, or descriptions before downloading.
All processing happens in your browser. Your JSON data never leaves your device.
OpenAPI specs use JSON Schema to define request bodies. Generate schemas from API responses instantly to retroactively document APIs.
Validate API requests, webhooks, or form submissions before they hit your logic. Libraries used include `ajv` (JS), `jsonschema` (Python), `gojsonschema` (Go).
VS Code uses JSON Schema for config files like `package.json`. Publish a schema for your config file to give users instant IntelliSense.
Data type (string, number, integer, boolean, object, array, null).
Array of property names that MUST be present.
Defines the schema for each named property in an object.
Defines the schema for elements within an array.
Restricts a value to a fixed set of allowed options.
Semantic validation hint (email, uri, uuid, date-time).
Numeric range constraints.
Regex pattern that a string must match.
The generator assumes all fields it sees are required. You must review the `required` array.
If sample has "status": "active", generator infers string. You might need to add an `enum` manually.
If a field is never null in your sample, the schema won't allow null. Add `type: ["string", "null"]` where needed.
A specification for describing the structure of JSON data. Used for validation, documentation, and contract testing.
Draft-07. It offers the best balance of features (conditional validation) and widespread library support.
Yes. The generator handles arbitrary nesting depth and builds recursive schemas.
Pass the schema to a library like `ajv` (JS) or `jsonschema` (Python) along with your data.
Yes. The output is editable. Add regex patterns, numeric ranges, or enums.
No, it generates schemas. Use our JSON Validator to validate data against a schema.
Yes, 100% free.
Yes. Client-side processing only.
Yes. Copy the `properties` block into your OpenAPI `components/schemas`.
Paste a real JSON sample above and get a production-ready JSON Schema in seconds.