JSON to GraphQL: Generate Type Definitions & Schema Boilerplate

From JSON to GraphQL API in Seconds

Building a GraphQL API from an existing REST API or database? The hardest part is writing all the type definitions. Paste a sample JSON response and get a complete SDL schema including types, input types, and Query/Mutation boilerplate.

GraphQL Scalar Mapping

• string → String
• integer → Int
• float → Float
• boolean → Boolean
• Field named id or _id → ID
• null → nullable (no ! modifier)

What Gets Generated

• type TypeName { ... } — Query return type
• input TypeNameInput { ... } — Mutation argument type
• type Query { get, list } — Sample query resolvers
• type Mutation { create, update, delete } — Sample mutations

// JSON Input
{ "id": "u1", "name": "Alice", "email": "a@example.com", "age": 28 }

// Generated GraphQL SDL
type User {
  id: ID!
  name: String!
  email: String!
  age: Int!
}

input UserInput {
  id: ID
  name: String
  email: String
  age: Int
}

type Query {
  getUser(id: ID!): User
  listUsers: [User!]!
}

type Mutation {
  createUser(input: UserInput!): User
  updateUser(id: ID!, input: UserInput!): User
  deleteUser(id: ID!): Boolean
}