How to Generate TypeScript Interfaces From JSON

To generate TypeScript interfaces from JSON, paste a representative JSON sample into the ByteTools JSON to TypeScript generator, set a root interface name, and click Generate. You get strongly-typed interfaces with nested types and optional keys, ready to copy into your project.

Hand-writing interfaces for an API response is tedious and drifts out of sync the moment the payload changes. This tutorial covers the full flow, what each behaviour does, and why running it in the browser keeps private payloads safe.

Step-by-step: JSON to TypeScript

1. Paste a representative sample. Include every field you want typed. The generator infers types recursively from the values it sees.
2. Set the root interface name. It defaults to Root; naming it User or ApiResponse gives code you can use without renaming.
3. Click Generate. The tool walks the structure, creates an interface for each object, names nested interfaces from their keys, and marks keys optional where they vary.
4. Copy or download. Send the interfaces to your clipboard or save them as a .ts file and import them.

A worked example

Given this input:

{
  "id": 1,
  "name": "Ada",
  "address": { "city": "Paris", "zip": "75000" },
  "tags": ["admin"]
}

the generator produces something like:

interface Address {
  city: string;
  zip: string;
}
interface Root {
  id: number;
  name: string;
  address: Address;
  tags: string[];
}

The nested address object became its own Address interface, referenced from Root, and the string array became string[].

What the inference rules mean

Why do it in the browser

All inference runs locally with JavaScript. Your JSON is never uploaded or stored, so you can generate types from private API responses, internal schemas, and unreleased structures without them leaving your device. As a PWA it also works offline once loaded.

Try the JSON to TypeScript generator — free and 100% in your browser.

FAQ

Do I need every field in the sample?

Include every field you want typed. The generator can only infer types for keys it sees, so missing keys will be absent from the interface.

What if an array is empty in my sample?

It types as unknown[]. Add at least one element so the element type can be inferred into a precise array type.

How are nested objects named?

They are named from their keys and referenced from the parent, with identical shapes deduplicated so you never get repeated interfaces.

Is the output valid TypeScript?

Yes. The result is valid interface code you can paste directly into a .ts file.

Related free tools

• JSON to Go Struct — the same idea for Go services.
• JSON Formatter — tidy your sample before converting.
• JSON Validator — confirm the sample is valid first.
• JSON to XML Converter — transform the same data to XML.

Built by ByteVancer

ByteTools is a free product of ByteVancer, a software and web development studio building web apps, SaaS, and custom software. When you need more than a converter, explore what ByteVancer can build.