Can it handle heterogeneous arrays with different object shapes?

Yes. When an array contains objects with differing keys, the generator unions the keys into a comprehensive interface where non-universal fields are marked as optional.

Does it support deeply nested JSON structures?

Yes. The recursive parser supports arbitrary nesting depths, generating separate named interfaces for each depth level to maintain clean, readable code.

Developer Utilities

JSON to TypeScript Interface Generator

The problem: Writing TypeScript type definitions by hand for complex, multi-tiered REST API responses is tedious and error-prone.

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Root name:

Interfaces

Output Lines

253 B

Input Size

JSON Input253 chars

TypeScript Interface

export interface Root {
  id: number;
  name: string;
  email: string;
  age: number;
  verified: boolean;
  address: Address;
  tags: string[];
  metadata: null | null;
}

export interface Address {
  street: string;
  city: string;
  zip: string;
}

JSON to TypeScript Interface Generator: the complete guide

The JSON to TypeScript Interface Generator automatically infers strongly typed TypeScript interfaces, type aliases, and nested object models from raw JSON payloads. Eliminate tedious manual type authoring for API responses, backend webhooks, and mock data fixtures with customizable root naming, optional field detection, and clean PascalCase naming conventions.

Automating Type Safety for Modern Frontend Architectures

Modern TypeScript frontend development requires strictly typed interfaces for every API endpoint consumed. Manually inspecting a 500-line JSON response from a REST API and writing corresponding TypeScript interfaces by hand is slow, tedious, and prone to typing bugs like confusing string timestamps with dates or overlooking nullable fields.

Our parser recursively traverses arbitrary JSON structures, identifies primitive types (string, number, boolean, null), constructs nested sub-interfaces for child objects, and unifies array elements into union types (e.g., Array<string | number>) in under 5 milliseconds.

Handling Nulls, Optional Properties, and Naming Conventions

Real-world API data frequently contains null or missing properties across different records. Our generator flags nullable values as optional or union types (e.g., property?: string | null) to prevent runtime undefined property access crashes.

Child objects are automatically extracted into distinct, reusable interface definitions named in idiomatic PascalCase derived from their parent key names, producing clean, production-ready code suitable for direct inclusion in your types/ directory.

Step by step: how to use JSON → TypeScript

1
Paste your raw JSON payload (object or array) into the left editor.
2
Specify your preferred root interface name (e.g., 'UserResponse' or 'ProductPayload').
3
Toggle between 'interface' and 'type' keyword definitions based on your team style guide.
4
Review the generated TypeScript code with clean syntax highlighting and automatic indentation.
5
Click 'Copy TypeScript' to copy the types directly into your IDE.

Security & privacy

JSON parsing and TypeScript AST generation operate exclusively client-side. Proprietary API payloads and sensitive mock data are never sent to external servers.