JSON to TypeScript Interface Generator (Free & Fast)

How to Convert JSON to TypeScript Interfaces

Manually writing TypeScript interfaces for complex API responses is tedious and error-prone. Follow these simple steps to automate the process:

• Step 1: Copy your JSON data (e.g., from a Postman response or API endpoint).
• Step 2: Paste the JSON into the input box above.
• Step 3: Click the “Convert to TypeScript” button.
• Step 4: Copy the generated `export interface` code directly into your `.ts` file.

When to Use This Tool

This converter is essential for any developer working with TypeScript in a modern web stack. It saves time and reduces errors in these common scenarios:

• Working with JSON API responses and requests: Quickly type the data coming from your backend (REST or GraphQL) without guessing properties.
• Debugging JSON syntax and structure issues: Visualize the structure of deep JSON objects to spot inconsistencies.
• Validating JSON configuration files: Ensure your `tsconfig.json`, `.prettierrc`, or custom config files match the expected schema.
• Testing and developing with JSON data: Generate mock interfaces for unit tests (Jest/Vitest) instantly.
• Learning and understanding JSON format: Great for beginners to see how raw data maps to strict types.
• Processing JSON for data analysis projects: creating types for large datasets before processing them in Node.js or Python.

Why Use This JSON to TypeScript Tool?

While there are many converters online, most are bloated or require server uploads. We built this tool specifically for frontend developers working with React, Angular, and Vue who need speed and security.

1. Privacy-First Architecture

Security is our top priority. Unlike other tools that send your data to a backend server for processing, this tool runs 100% in your browser using JavaScript. Your sensitive API keys, customer data, and proprietary logic never leave your device.

2. Smart Type Inference

We don’t just map strings to strings. Our engine intelligently analyzes your data to:

• Detect Arrays and generate `Type[]` definitions.
• Identify Nested Objects and create sub-interfaces recursively.
• Handle Null values gracefully by assigning `any` or nullable types.

3. Zero Latency (Offline Ready)

Because the logic is client-side, there is no network latency. The conversion happens instantly, even if you are on a slow connection or completely offline on an airplane.

Understanding JSON and TypeScript Interfaces

If you are new to TypeScript, you might wonder why this conversion is necessary. Here is a technical breakdown of the technologies involved.

What is JSON?

JSON (JavaScript Object Notation) is the standard data interchange format for the web. It is lightweight, text-based, and language-independent. However, JSON is “loosely typed,” meaning it doesn’t enforce strict rules about what data goes where.

What is a TypeScript Interface?

TypeScript adds “static typing” to JavaScript. An Interface defines the shape of an object. It acts as a contract that guarantees an object will have specific properties with specific types (e.g., `id` must be a `number`, `name` must be a `string`).

The Benefit of Conversion

When you fetch data from an API (JSON), TypeScript doesn’t automatically know what that data looks like. By converting that JSON into an Interface, you unlock:

• Autocomplete (IntelliSense): Your IDE (VS Code) will suggest properties as you type.
• Compile-Time Error Checking: If you try to access a property that doesn’t exist (e.g., `user.nmae` instead of `user.name`), TypeScript will warn you instantly.
• Self-Documentation: The interface serves as documentation for your team, explaining exactly what the API returns.

Explore More JSON Tools

Check out our other free developer utilities to streamline your workflow.

Frequently Asked Questions