JSON Schema Generator
JSON Input
Generated Schema (Draft 7)
Schema will appear here

Related Tools

See all ->
JSON FormatterFormat & validateJSON → TypeScriptInterface & type generatorYAML ↔ JSON ConverterBidirectional, auto-detectCSV → JSON ConverterTable preview & type inferenceAPI Mock GeneratorFake REST API with JSON schemaAPI Request Generator & TesterGenerate · Test · 12 langsDiff CheckerCompare text & codeRegex TesterTest & debug patterns

JSON Schema Generator — Infer schema from any JSON

Infer schema from any JSON. Runs in your browser.

Updated May 15, 2026
Share & Support

What's included

Features

Instant schema inference from any valid JSON — objects, arrays, nested structures
Type detection for string, number, integer, boolean, null, object, and array types
Nested object schemas with full properties and required arrays
Array items schema inferred from element types
JSON Schema Draft 7 output compatible with AJV, OpenAPI, and Pydantic
Required fields array populated from fields present in the input
Copy and download the generated schema as schema.json ready for use in your project
Runs entirely in the browser — JSON is never uploaded or sent to any server
Pairs with [JSON Formatter](/json-formatter/) for cleaning up and validating the input before generating the schema

About this tool

Generate JSON Schema From Any JSON in One Paste

Writing JSON Schema by hand is meticulous work. Every field needs a type, every object needs a properties definition, every array needs an items schema, and required fields need to be listed explicitly. For complex API response structures with multiple levels of nesting, writing the schema from scratch takes far longer than the JSON itself.

This JSON Schema generator takes the opposite approach: paste your JSON, and the schema is inferred automatically. Every field is analyzed, its type is determined (string, number, integer, boolean, null, object, array), and the schema structure mirrors the JSON hierarchy. Nested objects produce nested schema definitions with their own properties. Arrays produce items schemas based on the array element types.

Required fields are inferred by presence. If a field appears in the top-level object, it is added to the required array. For arrays of objects, fields that appear in all sampled items are marked required. This gives you a useful starting schema that you can then edit to add optional fields, enum values, format constraints, and descriptions.

JSON Schema Draft 7 is the most widely supported version. The output is compatible with AJV (the most popular Node.js validator), OpenAPI 3.0 with draft-07 semantics, Pydantic, FastAPI, and most JSON validation libraries across all major programming languages.

Editing the generated schema. The inferred schema is a starting point — not the final schema. After generating, edit the required array to remove fields that are truly optional in your API. Add format constraints (”format”: “email”, ”format”: “date-time”) to string fields that have semantic meaning. Add minimum and maximum to numeric fields. Add enum arrays to string fields with fixed allowed values. Add description strings to each property for documentation purposes. These edits turn an inferred schema into a precise, production-ready validation contract.

Runs fully in your browser — JSON is never uploaded or processed by any server.

Step by step

How to Use

  1. 1
    Paste your JSONPaste a JSON object, array, or any valid JSON value into the input panel. The schema is generated immediately on paste.
  2. 2
    Review the inferred schemaCheck the generated schema. Every field from your JSON appears with an inferred type. Nested objects and arrays are fully expanded in the schema structure.
  3. 3
    Adjust required fieldsThe generator marks all present fields as required by default. Edit the required array to remove optional fields that may be absent in some responses.
  4. 4
    Add constraints and descriptionsManually add format, pattern, minimum, maximum, enum, or description fields to the generated schema for validation purposes.
  5. 5
    Copy or downloadCopy the schema to clipboard or download as schema.json for use in your project or API documentation.
  6. 6
    Validate JSON against the schemaUse the downloaded schema.json with AJV, Ajv-cli, or your preferred validator to verify that new JSON payloads conform to the inferred structure. Pair with JSON Formatter to inspect and clean up the input before generating.

Real-world uses

Common Use Cases

◉
Generate schemas for API response validation
Paste an API response and generate a JSON Schema Draft 7 schema to use with AJV, Zod, or your validation library of choice.
▦
Create OpenAPI component schemas
Use the generated schema as a starting point for OpenAPI 3.0 component definitions — paste into your spec and refine as needed. Prototype the endpoints themselves in the REST API builder playground.
△
Bootstrap Pydantic models from JSON
Generate a JSON Schema from a Python dict or FastAPI response body and use it to build Pydantic model field definitions.
✦
Document data structures in API specs
Generate and edit schemas for request bodies and response types to include in API documentation or a developer portal.
⚡
Validate config files with a schema
Create a schema from an example config JSON and use it to validate future config files against the expected structure.
≡
Skip manual schema writing for prototypes
Generate an approximate schema quickly during development without writing every property, type, and required definition by hand. Need typed models instead? Convert the same JSON with JSON to TypeScript, or tidy it first in the JSON formatter.

Got questions?

Frequently Asked Questions

Paste your JSON into the input panel. The tool analyzes every field and produces a JSON Schema with inferred types, properties definitions, and required arrays.

The output is JSON Schema Draft 7. This is compatible with AJV, OpenAPI 3.0 with draft-07 semantics, Pydantic, and most modern JSON validation libraries.

Fields present in the top-level object are added to the required array by default. You can edit the schema to remove optional fields from the required list.

Yes. Nested objects produce nested schema definitions with their own properties and required arrays. Arrays produce items schemas based on the element types found in the array.

Yes, as a component schema. OpenAPI 3.0 supports JSON Schema Draft 7 for request bodies, response schemas, and component definitions. Minor adjustments may be needed for nullable fields.

No. All schema inference runs in your browser. Your JSON is never sent to any server.