JSON to Typescript

JSON to TypeScript — Type Generation Guides

When you fetch data from an API or read a JSON file, TypeScript needs to know the shape of that data to give you type safety. Converting JSON to TypeScript interfaces is a common task — and doing it manually for complex, deeply nested JSON structures is tedious and error-prone.

This category covers how to generate TypeScript types from JSON: the patterns, tools, and best practices for keeping your TypeScript interfaces accurate and maintainable.

Topics Covered

• Interface vs. type alias — When to use interface and when to use type for JSON shapes
• Nested objects — Handling deeply nested JSON with composed interfaces
• Optional and nullable fields — ?, null, undefined, and real-world API inconsistencies
• Array types — Typing JSON arrays, heterogeneous arrays, and discriminated unions
• API response typing — Wrapping REST and GraphQL responses with correct TypeScript types
• Automatic generation tools — JS2TS, quicktype, and json-to-ts libraries

Browse the articles below or use JS2TS to instantly generate TypeScript interfaces from any JSON.