JSON to TypeScript Converter
Turn a JSON sample into TypeScript interfaces or type aliases, with nested types and optional fields.
export interface User {
id: number;
name: string;
email: null;
roles: string[];
profile: Profile;
posts: Post[];
}
export interface Post {
title: string;
tags: (string | unknown)[];
draft?: boolean;
}
export interface Profile {
website: string;
followers: number;
}
Keys missing from some array items become optional. A field holding both values and null shows as a union.
How to use
Paste a representative JSON sample into the input.
Name the root type and choose interface or type alias.
Copy the generated declarations into your project.
Example
Optional field from an array
draft appears in only one array item, so it is optional.
{"posts":[{"title":"A"},{"title":"B","draft":true}]}export interface Root {
posts: Post[];
}
export interface Post {
title: string;
draft?: boolean;
}Frequently Asked Questions
No. Types are inferred from the one sample you paste, so a field that is sometimes a string and sometimes a number only shows both if both appear. Review the output against the API documentation.
Capabilities
- Nested interfaces
- Optional keys inferred from arrays
- Union types
- Interface or type alias output
- Readonly option
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