JSON to TypeScript Converter

How to Use the JSON to TypeScript Converter

The JSON to TypeScript Converter transforms raw JSON data into clean, well-structured TypeScript interfaces in seconds. Whether you're consuming REST APIs, working with configuration files, or migrating a JavaScript project to TypeScript, this tool eliminates the tedious manual process of writing type definitions by hand.

Step-by-Step

1. **Paste your JSON** into the input panel on the left side of the editor.

Set a root interface name — by default it uses RootObject, but rename it to match your domain (e.g., UserProfile, ApiResponse).

3. **Click Convert** to generate TypeScript interfaces instantly.

4. **Copy the output** using the clipboard button or download it as a .ts file.

5. **Fine-tune** optional fields or union types as needed for your specific use case.

Features

Nested Object Support — Deeply nested JSON objects are converted into separate named interfaces, keeping your type definitions clean and reusable.

Array Type Inference — Arrays of objects automatically generate their own interface. Mixed arrays produce union types like (string | number)[].

Optional Field Detection — When multiple JSON samples are provided, fields that don't appear in every record are marked as optional with ?.

Enum Suggestion — Repeated string values with a small set of options are flagged as potential enum candidates.

Export Declarations — All interfaces are exported by default, ready to be imported across your project.

Client-Side Processing — Your data never leaves the browser. All conversion happens locally using JavaScript.

Common Use Cases

API Integration — Paste a sample API response to instantly generate TypeScript interfaces for your frontend service layer.

Database Schema Typing — Convert MongoDB documents or Firestore snapshots into TypeScript interfaces for type-safe database queries.

Configuration Files — Generate types for package.json, tsconfig.json, or custom configuration files.

Code Migration — Accelerate JavaScript-to-TypeScript migrations by auto-generating interfaces from existing JSON fixtures.

Mock Data — Create type-safe mock data factories by first generating interfaces from sample JSON payloads.

Why Use This Tool

Manually writing TypeScript interfaces from JSON is error-prone and time-consuming, especially with deeply nested structures. This converter handles edge cases like nullable fields, mixed arrays, and recursive types that are easy to miss by hand. It saves minutes on every API integration and ensures your types accurately reflect the data you're working with. Everything runs client-side, so sensitive data like API keys or user records never touch a third-party server.