JSON to TypeScript Interface Generator

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

This generator converts a JSON sample into TypeScript interfaces with type annotations, running entirely in your browser. It infers string, number, boolean, array, null, and object types, and pulls nested objects out into separate named interfaces.

The generated code uses proper exports, optional markers, and references between interfaces so it slots into a real codebase.

1. Copy your JSON data and paste it into the input textarea above.
2. Toggle nullable field detection and nested object depth options as needed.
3. Click Generate, then copy the TypeScript interfaces or download the .ts file.

When to Use JSON to TypeScript

Typing your API responses by hand is tedious and drifts quickly; this generator matches the data to the types in one step. When you fetch from an endpoint, the response JSON becomes an interface that documents the exact shape your code will receive, which is the foundation of type-safe data fetching. The same approach applies to configuration files and mock data, producing definitions you can reuse across a project.

Nullable detection matters for real APIs. Real responses routinely contain fields that can be null, and with the option enabled those fields are typed as a union with null instead of pretending they are always present. Nested objects become separate named interfaces that reference one another, keeping large models readable. The output is a starting point: review it, tighten types, and adjust optionality based on your actual contract rather than the sample alone.

JSON to TypeScript Tips and Best Practices

1. Include all possible fields and edge cases, including null values and empty arrays, or those fields simply will not appear in the generated interface.
2. Enable nullable detection when the target is a real API, since optional fields are common and deserve correct types.
3. Review and refine generated interfaces, changing types where the sample is misleading, such as a number that should be an enum.
4. Prefer interfaces for object shapes; type aliases follow a similar pattern using the type keyword.

Why Client-Side Privacy Matters for Type-Safe API Client and Data Model Development

The JSON you convert to interfaces is a mirror of your data model, and samples frequently carry realistic values from live responses. Uploading that to a generator hands an external service a description of your internal structures.

This JSON to TypeScript generator produces interfaces entirely in your browser, so your sample data never leaves your device. You can type confidential models and contracts without exposing their shape to a third party.