Reads the document's actual shape — nesting, array element types, which fields are ever
null or missing — and generates a matching TypeScript interface.
A field missing from some records becomes field?: T; one that's sometimes literally
null becomes field: T | null. Nested objects get their own named interface.
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Have a JSON response, config file, or API payload and want a proper TypeScript type for it instead of typing
any? Generate a real interface in one click, entirely in your browser.
Json Web Viewer's Types mode reads your document's actual shape — property names, nesting,
array element types, whether a value is ever null — and generates a matching TypeScript
interface, ready to paste into your codebase. No server round-trip, no account, no upload.
The same engine also generates Go structs, Rust structs, Python dataclasses, Java records, C# records, and Kotlin data classes from the exact same document — switch languages from the dropdown next to the mode buttons rather than re-pasting your JSON into a different tool for each target language.
Example — this JSON:
{
"id": "ord_9f21a",
"customer": {
"name": "Ada Lovelace",
"email": "ada@example.com",
"vip": true
},
"items": [
{ "sku": "book-001", "qty": 2, "price": 19.99 },
{ "sku": "mug-014", "qty": 1, "price": 12.5 }
],
"shippedAt": null
}generates this TypeScript:
interface Root {
id: string;
customer: Customer;
items: Item[];
shippedAt: null;
}
interface Customer {
name: string;
email: string;
vip: boolean;
}
interface Item {
sku: string;
qty: number;
price: number;
}
Open this example in the editor →
The link above pre-loads the order example above into Types mode. TypeScript is the
default — select Go or Rust from the language dropdown to regenerate the
same document in either of those instead.
No. Type generation runs entirely in your browser — your JSON never leaves the page.
Yes. Types mode has a language dropdown next to the mode buttons — select Go, Rust, Python, Java, C#, or Kotlin from it and the same document regenerates in that language. TypeScript is just the default.
Nested objects become nested interfaces, arrays become typed array properties, and a field that's
null in the sample or missing from some array elements is generated as optional/nullable
rather than forcing a type that doesn't match the real data.
Need to check your JSON's shape against a formal schema instead of a language type? See JSON Schema Generator.