JSON to Interface Online — TypeScript Interface Generator
Auto-generate TypeScript interfaces from any JSON — nested objects · optional fields · readonly · export · 100% Free
export interface User {
id: number;
name: string;
active: boolean;
address: Address;
}Quick TypeScript interface generation without leaving your browser. Paste JSON from your API, Postman, or browser DevTools network panel and get production-ready TypeScript interfaces instantly. Ideal for developers integrating new API endpoints who need to quickly bootstrap their types before writing business logic.
What is JSON to TypeScript Interface Generation?
This tool analyses the structure of your JSON data and automatically generates TypeScript interface or type declarations — saving you the time of writing them manually. It infers string, number, boolean, null, nested object interfaces, and typed arrays. When your JSON is an array of objects, optional fields are detected automatically.
How Nested Objects Are Handled
Every nested JSON object generates its own named TypeScript interface. For example, if your JSON has "address": { "city": "Ahmedabad" }, the tool generates a separate Address interface and references it as address: Address in the parent interface — matching real-world TypeScript project structure.
Frequently Asked Questions
How do I copy JSON from browser DevTools to generate TypeScript?
In Chrome DevTools: (1) Open Network tab. (2) Click the API request. (3) Click Response tab. (4) Right-click → Copy Response. Paste here → generate TypeScript. Alternative: click "Preview" tab → right-click root object → "Store as global variable" → copy(temp1) in Console copies formatted JSON.
Can I generate TypeScript interfaces for GraphQL query results?
Yes — GraphQL responses are JSON with {"data": {...}} structure. Paste the response here and generate interfaces for the nested data object. For production GraphQL TypeScript integration, use graphql-code-generator with your schema and queries — it generates precise types including exact fields from your query selection set.
What naming convention does the TypeScript interface generator use?
By default: object keys are used as interface names (PascalCase). Array item interfaces: parent key name singular + capitalized. Examples: "products" array → Products interface. "userData" object → UserData interface. "items" array → Items interface. You can rename generated interfaces in your codebase — generation gives a starting point, not a final answer.
How do I handle JSON with dynamic keys in TypeScript?
Dynamic/computed keys (like {"user_123": {...}, "user_456": {...}}) can't be represented as specific interfaces. Use index signatures: interface UserMap { [key: string]: UserData; }. Or use TypeScript Record type: type UserMap = Record<string, UserData>. The generator detects this pattern and generates appropriate index signatures.