JSON to TypeScript & Zod Schema Generator
Convert JSON objects into typed TypeScript interface definitions or Zod validation schemas instantly.
How do I use JSON to TypeScript & Zod Schema Generator?
Paste a JSON response payload into the input editor or click 'Sample' to load a nested API object.
Configure your root interface name (`RootObject`), toggle `interface` vs `type`, and enable optional (`?`) or `readonly` modifiers.
Copy the generated TypeScript declarations directly into your `.ts` or `.d.ts` type definitions file.
What features does JSON to TypeScript & Zod Schema Generator offer?
Reads your JSON and figures out the right TypeScript type for each field automatically
Handles nested objects and arrays — it generates child interfaces for each level
Supports both TypeScript interface style and type alias style output
Can generate Zod schemas ready for use with React Hook Form or API validation
Runs entirely in your browser — no JSON data is ever sent to a server
JSON Runtime Types to TypeScript Static Type Mapping
The AST inference engine inspects every key and value across nested objects and homogeneous/heterogeneous arrays to emit strict TypeScript interfaces.
| JSON Input Pattern | Inferred TypeScript Type | Strict Null / Optional Handling | Example Output |
|---|---|---|---|
| Primitive scalars | string | number | boolean | Exact primitive type | readonly id: number; |
| Homogeneous array | T[] or Array<T> | Merges object keys across items | items: OrderItem[]; |
| Heterogeneous array | (string | number)[] | Union of all observed element types | tags: (string | number)[]; |
| Null or missing key | T | null / key?: T | Emits nullable union or optional ? | deletedAt?: string | null; |
Frequently Asked Questions about JSON to TypeScript & Zod Schema Generator
How does the converter handle arrays of objects where some keys are missing in certain elements?
The inference engine performs a structural union across every object in the array. Keys present in all elements are emitted as required properties, while keys missing from at least one element are marked optional (`key?: Type`).
Should I generate TypeScript `interface` or `type` aliases for API payloads?
Use `interface` when you need declaration merging, `extends` inheritance, or faster TypeScript compiler caching in large projects. Use `type` aliases when you need union types, tuple definitions, or mapped utility types.
What happens if a JSON field value is `null` in my sample payload?
If a property is `null` in every sampled object, it is typed as `null` (or `unknown | null`). Provide at least one non-null example in your JSON array so the engine can infer `string | null` or `number | null`.
How are JSON keys containing hyphens or spaces (like `content-type`) typed?
Any JSON property key that is not a valid ECMAScript identifier (such as keys containing hyphens, spaces, or leading digits) is automatically wrapped in string quotes in the TypeScript interface (`"content-type": string;`).
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