JSON to GraphQL Type Generator

How to Use the Free Client-Side JSON to GraphQL Generator

This generator creates GraphQL type definitions from a JSON sample, running entirely in your browser. It adds non-null markers where values are consistent, list brackets for arrays, and extracts nested objects into separate types.

Fields with null values in the sample are marked nullable, while consistently present fields get the non-null marker.

1. Copy your JSON data and paste it into the input textarea above.
2. Toggle nullable detection and type naming preferences.
3. Click Generate, then copy the GraphQL type definitions or download the .graphql file.

When to Use JSON to GraphQL

Designing a GraphQL schema by hand means inventing types from memory; this generator grounds them in the actual payload. When you have a sample API response, you generate the output type definitions that document it, then use them as the basis for your server schema. It is a natural tool during GraphQL server prototyping and when planning a migration from a REST endpoint to a GraphQL API, since the existing response becomes the type contract.

The generator emits only output type definitions, with input types and enums left for you to add, which keeps the initial schema honest about what it knows. Nullable detection reads the sample: fields that appear as null become nullable, fields that are always present become non-null, and array items are marked based on whether nulls appear inside the array. Nested objects become their own types with proper field references, so the schema stays modular rather than one giant type.

JSON to GraphQL Tips and Best Practices

1. Include every field that exists in your API in the sample, because fields missing from the sample will be absent from the generated types.
2. Review the non-null markers, since they are inferred from data and not from your actual schema requirements.
3. Extend the generated output types with the input types and enums your mutations need.
4. Rename the generated types to match your schema conventions before committing them.

Why Client-Side Privacy Matters for GraphQL Schema Design from Sample Payloads

The sample payloads you convert to types are snapshots of your real data, including field names and structures that internal systems depend on. Sending them to an online generator exposes your schema design before it is even public.

This JSON to GraphQL generator processes everything locally in your browser, so your payloads never leave your device. You can design schemas for private APIs without a third party seeing your data model.