JSON to GraphQL Converter – Generate GraphQL Schema

How to Convert JSON to GraphQL Schema

Manually writing GraphQL Schema Definition Language (SDL) is repetitive and prone to typo errors. This tool analyzes your raw data and constructs a strict type system. Here is the workflow:

• Step 1: Input Data: Copy a valid JSON response from your existing REST API, database dump, or Postman.
• Step 2: Processing: Paste it into the editor. Our engine scans every field, detecting primitives (Strings, Ints, Floats) and complex nested objects.
• Step 3: Generate: Click “Convert.” The tool recursively builds `type` definitions for every object found.
• Step 4: Integration: Copy the output directly into your Apollo Server `schema.graphql` or frontend fragment definitions.

Technical Deep Dive: REST vs. GraphQL Types

Moving from REST to GraphQL requires a shift in mindset from “Resources” to “Types.” This tool bridges that gap by mapping JSON values to GraphQL’s strict typing system.

Type Mapping Logic

Here is exactly how our engine maps your JSON data to GraphQL scalars:

Why Strong Typing Matters

In REST, the payload structure is implicit. In GraphQL, it is explicit. By converting your JSON to a schema, you create a Contract. This contract allows frontend developers to use tools like GraphQL Code Generator to auto-generate TypeScript interfaces, ensuring that if the backend changes a field type, the frontend build will fail safely before deploying to production.

Why Developers Trust This Tool

We built this converter with the specific needs of Full-Stack and Backend engineers in mind.

1. Enterprise-Grade Privacy (GDPR Compliant)

API schemas often reveal your database structure or internal business logic. Most online converters process data on their servers, creating a potential leak. This tool operates 100% Client-Side. Your JSON data is processed using JavaScript in your browser’s memory and is never transmitted over the internet.

2. Intelligent “ID” Detection

Standard converters treat `id: 1` as an `Int`. However, in the GraphQL world, IDs are a unique scalar type used for caching (like Apollo Client normalization). Our algorithm specifically looks for keys named `id`, `_id`, or `uuid` and correctly assigns them the `ID` type instead of a generic String or Int.

3. Handling “Dirty” Data

Real-world data is messy. You might have an array with mixed types or null values. This tool attempts to infer the “best common type” for arrays and generates nullable fields by default (omitting the `!`), which is the safest approach for production APIs to prevent null-pointer crashes.

Troubleshooting Common Issues

If the generated schema doesn’t look right, check these common JSON pitfalls:

• Empty Arrays `[]`: If an array is empty, the tool cannot guess what’s inside. It defaults to `[String]`. You may need to manually update this to your specific type.
• Null Values: If a field is `null` in your JSON, we default to `String` (nullable). You should verify these fields against your database schema.
• Naming Collisions: If you have two different objects named “User” (one in metadata, one in data), the tool might merge them. Ensure your JSON keys are distinct if they represent different entities.

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Frequently Asked Questions