How to Convert JSON to TypeScript Interfaces (the Fast Way)

Hand-writing TypeScript interfaces for every API response is tedious and error-prone. A typo in a property name or the wrong type (string instead of number) can hide bugs until runtime. The good news: you can generate accurate interfaces straight from a sample JSON payload.

Our free JSON to TypeScript converter does this instantly in your browser — no upload, no account.

Why generate types from JSON?

• Catch shape mismatches at compile time instead of in production.
• Autocomplete everywhere — your editor knows every field.
• Self-documenting code — the interface is the contract.

The rules behind the conversion

When you paste JSON, the converter walks the structure and infers a type for every value:

JSON value	TypeScript type
"hello"	string
42	number
true	boolean
null	null
{ ... }	a new interface
[ ... ]	T[] (element type inferred)

Nested objects become their own interfaces

Given this payload:

{
  "id": 1,
  "profile": { "city": "London", "age": 36 }
}

you get:

interface Profile {
  city: string;
  age: number;
}

interface Root {
  id: number;
  profile: Profile;
}

Arrays infer their element type

["a", "b"] becomes string[], and an array of objects produces a reusable item interface.

A quick workflow

1. Hit a real API endpoint and copy the response.
2. Clean it up with the JSON Formatter if it's minified.
3. Paste it into JSON to TypeScript and copy the result into your project.

Working in Go instead? The same idea applies — use JSON to Go Struct to generate structs with correct json tags.

Tips for production-quality types

• Sample more than one record. A single object can't tell you which fields are optional. If a field is sometimes missing, mark it with ?.
• Watch for null vs missing. "x": null becomes null; you may want string | null.
• Rename the root. Give the root interface a meaningful name like User or ApiResponse rather than the default Root.

Generate your interfaces now with the JSON to TypeScript converter.