JsonifyTools
    Schema Toolkit · 100% Local · Browser Only

    JSON Schema to OpenAPI

    Generate OpenAPI 3.1 components, GET examples, POST request bodies, and YAML/JSON export from a JSON Schema.

    Browser only Valid Schema / Data
    JSON Schema
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    OpenAPI 3.1 Spec
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    Schema Metrics

    Fields
    12
    Objects
    2
    Arrays
    1
    Constraints
    4

    Field Hierarchy Tree

    ❖Root(object)
    └─id*(integer)
    └─name*(string)
    └─email*(string)
    email
    └─active(boolean)
    └─createdAt(string)
    date-time
    └─profile(object)
    └─phone(string)
    └─country(string)
    └─company(string)
    └─roles(array)
    └─items[](string)

    Schema Constraints

    $.name(1 rule)
    minLength:1
    $.email(1 rule)
    format:email
    $.createdAt(1 rule)
    format:date-time
    $.roles[](1 rule)
    enum:["admin","developer","member"]
    OpenAPI 3.0 & 3.1 Spec Generator
    Swagger UI & Redoc Compatible

    Convert JSON Schema to OpenAPI 3.0, 3.1 & Swagger YAML

    Convert JSON Schema specifications into OpenAPI 3.0 YAML, OpenAPI 3.1 JSON, and Swagger 2.0 definitions. Easily generate components/schemas, REST path operation payloads (requestBody & responses), and OpenAPI specifications for Swagger UI, Redoc, Postman, and AWS API Gateway.

    OpenAPI Specs3.0.3 & 3.1.0 Ready
    Legacy SupportSwagger 2.0 YAML
    Nullable Mappingnullable: true Conversion
    Privacy100% Client-Side

    Interactive OpenAPI Output Modes

    Select a target OpenAPI / Swagger format to inspect input JSON Schema and generated spec YAML:

    OpenAPI 3.0 YAML
    Input JSON Schema

    1. OpenAPI 3.0 YAML Component Schema

    Converts JSON Schema Draft-07 objects into OpenAPI 3.0 YAML component schemas, mapping `type: ['string', 'null']` to OpenAPI 3.0 `nullable: true`.

    Source JSON Schema
    {
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "required": ["userId", "email"],
  "properties": {
    "userId": { "type": "integer" },
    "email": { "type": "string", "format": "email" },
    "role": { "type": "string", "enum": ["ADMIN", "USER"] },
    "bio": { "type": ["string", "null"] }
  }
}
    Generated OpenAPI Spec YAML / JSON
    openapi: 3.0.3
components:
  schemas:
    UserProfile:
      type: object
      required:
        - userId
        - email
      properties:
        userId:
          type: integer
        email:
          type: string
          format: email
        role:
          type: string
          enum:
            - ADMIN
            - USER
        bio:
          type: string
          nullable: true
    Spec Conversion Rules

    JSON Schema vs OpenAPI 3.0 vs OpenAPI 3.1 Mapping Matrix

    Comparison matrix detailing keyword translation rules across JSON Schema and OpenAPI specifications:

    Feature / KeywordJSON Schema StandardOpenAPI 3.0 TranslationOpenAPI 3.1 Translation
    Schema Container$defs / definitionscomponents/schemascomponents/schemas
    Nullable Stringstype: ["string", "null"]type: string, nullable: truetype: ["string", "null"]
    Schema Header$schema URIopenapi: 3.0.3openapi: 3.1.0
    ID Identifier$id: '...' Removed (uses object key)$id / $anchor supported
    Sample Valuesexamples: [...]example: '...'examples: [...]
    Read-Only FieldsreadOnly: truereadOnly: truereadOnly: true

    Why, When, & How to Convert JSON Schema to OpenAPI

    Why Convert to OpenAPI?

    OpenAPI (Swagger) is the universal industry standard for REST API documentation, interactive UI sandboxes (Swagger UI / Redoc), SDK client generation, and API Gateway request validation.

    When to Use the Converter?

    Use when publishing public API documentation portals, generating OpenAPI contracts for Postman collections, configuring AWS API Gateway validation, and designing microservice contracts.

    How Does the Generator Work?

    Paste your JSON Schema. The converter translates `$defs` into `components/schemas`, handles OpenAPI 3.0 `nullable: true` rules, and formats a validated OpenAPI 3.0 or 3.1 YAML document in real time.

    Programmatic Conversion Code Examples

    Convert JSON Schema to OpenAPI in Node.js scripts, Python pipelines, and CLI builds:

    const { toOpenApi } = require('@openapi-contrib/json-schema-to-openapi-schema');

const jsonSchema = {
  type: 'object',
  required: ['id', 'name'],
  properties: {
    id: { type: 'integer' },
    name: { type: 'string' },
    email: { type: ['string', 'null'], format: 'email' }
  }
};

// Convert JSON Schema Draft-07 to OpenAPI 3.0 Schema
const openApiSchema = toOpenApi(jsonSchema);

console.log(JSON.stringify(openApiSchema, null, 2));
/* Output:
{
  "type": "object",
  "required": ["id", "name"],
  "properties": {
    "id": { "type": "integer" },
    "name": { "type": "string" },
    "email": { "type": "string", "nullable": true, "format": "email" }
  }
}
*/

    Frequently Asked Questions (FAQs)

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