JSON to TypeScript

What is JSON → TS?

The JSON to TypeScript generator infers TypeScript interface or type definitions directly from a sample JSON document, auto-generating nested types with structural deduplication so you never write boilerplate API response types by hand.

How it works

We walk the parsed JSON tree recursively and emit a TypeScript interface or type for every object shape encountered. Objects with identical key/value type patters are deduplicated into a single named type, so the output stays concise even for large documents with repeated sub-structures.

1. Paste JSON sample. Drop a .json file or paste a JSON object or array — for example, a real API response from your app.
2. Configure naming and style. Choose interface vs type alias, PascalCase vs camelCase, and whether to enable structural deduplication.
3. Copy or download. Copy the generated .ts code to clipboard or download as a types.ts file ready to import into your project.

Examples

{ name: 'Alice', age: 30 }

Generates `export interface Root { name: string; age: number; }`.

Nested + dedup

An array of user objects with a shared address shape generates separate User and Address interfaces, each defined once.

Common mistakes

Dedup off for very large documents

With dedup disabled, repeated object shapes each get an inline anonymous type, making the output much longer.

Null vs optional fields

A field with `null` in one sample and `string` in another becomes `string | null`. The tool does not yet infer optionality from multiple samples.

Alternatives

JSON Schema Generator

Generate formal JSON Schema instead of TypeScript types.

JSON Formatter

If you only need to read the JSON, not generate types, use the Formatter.

Frequently asked questions