JSON to TypeScript: Generate Types Automatically in 2026

Working with JSON APIs in TypeScript? Generating types from JSON data saves hours and prevents bugs. Why Generate Types? Without types: const data = await fetch ( ' /api/users ' ). then ( r => r . json ()); console . log ( data . name ); // No autocomplete, no type checking With generated types: interface User { id : number ; name : string ; email : string ; roles : string []; } const data : User = await fetch ( ' /api/users ' ). then ( r => r . json ()); console . log ( data . name ); // Full autocomplete + type checking interface vs type // interface - extendable, better for objects interface User { id : number ; name : string ; } // type - better for unions, intersections type Status = ' active ' | ' inactive ' ; type UserWithStatus = User & { status : Status }; Handling Optional Fields interface ApiResponse { id : number ; name : string ; email ?: string ; // Optional avatar : string | null ; // Nullable } Runtime Validation with Zod import { z } from ' zod ' ; const UserSchema = z