Last reviewed August 24, 2026

How to Generate TypeScript Interfaces from JSON

Infer deterministic nested TypeScript declarations from JSON objects without executing input.

Use representative JSON

Use an object or array of objects that represents the shapes your code actually receives. More representative array items provide better evidence for optional and nullable properties.

Understand type inference

Objects become named declarations, arrays become typed arrays, primitives retain JavaScript primitive types, and null becomes a union where evidence supports it.

Review generated names and properties

Unsafe identifier keys remain quoted. Nested type names are normalized deterministically, but domain-specific names may still be worth editing.

Know what samples cannot prove

A sample cannot prove every production variant. Optional properties are inferred only when records provide evidence, and validation logic is not generated.

Treat JSON only as data

The converter calls no runtime source, eval, schema service, or network destination.

Try the browser tool

Work with your file locally.

Open JSON to TypeScript