GraphQL Schema to OpenAPI Converter

Convert GraphQL SDL types, queries, and mutations into clean OpenAPI 3.0 YAML or JSON in your browser.

At a glance

GraphQL Schema to OpenAPI Converter transforms GraphQL SDL types, queries, and mutations into valid OpenAPI 3.0 and 3.1 specifications in YAML or JSON. It maps Query operations to GET endpoints, Mutations to POST endpoints, and object types into components.schemas in browser memory.

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100% Client-Side In-Browser GraphQL SDL to OpenAPI Transpiler

Compile GraphQL SDL types, queries, and mutations directly into standardized OpenAPI 3.0/3.1 YAML and JSON in browser memory.

Pure In-Browser
Presets:
Valid SDL 0 chars
OpenAPI Generation Options
0 chars
0 endpoints
OpenAPI Topology:
Paths 0
Schemas 0
Enums 0
Unions 0

Why Use This GraphQL Schema to OpenAPI Converter?

100% Client-Side Privacy: Your GraphQL schemas never leave your device or touch any external server.
Automatic REST Endpoint Mapping: Translates Query operations to GET paths and Mutations to POST paths with request bodies.
Components Schema Extraction: Compiles GraphQL object types, inputs, enums, and unions into OpenAPI 3.0 components.
Dual YAML and JSON Export: Choose between clean human-readable YAML or strict OpenAPI JSON schemas.
Rich Documentation Preservation: Maps GraphQL docstrings directly into OpenAPI operation summaries and descriptions.

How to Use GraphQL Schema to OpenAPI Converter

1

Input GraphQL SDL Schema

Paste your GraphQL schema definitions into the editor, or choose one of the built-in presets.

2

Configure OpenAPI Options

Select your desired output format (YAML or JSON), OpenAPI version (3.0.3 or 3.1.0), and indentation depth.

3

Copy or Download Specification

Copy the generated OpenAPI definition directly to your clipboard or download it as a .yaml or .json file.

GraphQL Schema to OpenAPI 3.0 example

Demonstrates transpiling a GraphQL SDL Query and User type into an OpenAPI 3.0 GET endpoint with query parameters and components.schemas.

GraphQL SDL Input Source 
type Query {
  user(id: ID!): User
}

type User {
  id: ID!
  name: String!
  email: String
}
Generated OpenAPI 3.0 YAML Processed 
openapi: 3.0.3
info:
  title: GraphQL API
  version: 1.0.0
paths:
  /api/user:
    get:
      operationId: user
      parameters:
        - name: id
          in: query
          required: true
          schema:
            type: string
      responses:
        '200':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/User'

Technical Specifications & Engine Details

Technical specifications and engine details for GraphQL Schema to OpenAPI Converter
Specification Details
Supported Formats TEXT/PLAIN, APPLICATION/GRAPHQL, .GRAPHQL, .GQL → APPLICATION/YAML, APPLICATION/JSON, TEXT/YAML, TEXT/PLAIN, .YAML, .JSON
Execution Mode 100% Client-Side In-Browser (client)
Browser Requirements Modern browser with JavaScript enabled.
Performance Constraints Runs client-side in browser memory. Performance and file limits are bounded by available local device RAM.
Maintained by Pragyan Pahadi

100% Client-Side Privacy Guarantee

Your schema files remain strictly on your local device. Zero data is transmitted to external servers.

Frequently Asked Questions

How are GraphQL Query and Mutation operations mapped to OpenAPI?
Fields inside type Query are converted to HTTP GET endpoints under /api/{fieldName}, with field arguments mapped to query parameters. Fields inside type Mutation are converted to HTTP POST endpoints with arguments mapped to requestBody schemas.
How are GraphQL non-null assertions (!) represented in OpenAPI?
Fields or arguments marked with the GraphQL non-null modifier (!) are added to the required array of the containing OpenAPI schema or parameter definition.
Are GraphQL Unions and Enums supported?
Yes. GraphQL Enums are mapped to OpenAPI string schemas with an enum array, and Unions are mapped using the standard OpenAPI oneOf schema composition keyword.
Is my schema data sent to any third-party server?
No. The entire transpilation pipeline runs 100% in your local browser sandbox with zero network calls and zero server logging.

Methodology

This tool runs entirely in your browser. The example above shows a representative input and the result it produces.

Last updated .

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