JSON to TypeScript

Our advanced JSON to TypeScript converter transforms JSON objects into TypeScript interfaces with a single click. Perfect for developers working with APIs, TypeScript projects, and data modeling.

Privacy Guaranteed: Your JSON data is processed locally in your browser. Nothing is stored or sent to any server.

Why Convert JSON to TypeScript?

Type Safety

Add strong typing to your JavaScript code to catch errors at compile time, leading to more robust and maintainable applications.

Improved Developer Experience

Get intelligent autocompletion, documentation, and error checking in your code editor, speeding up the development process.

API Contract Enforcement

Create accurate TypeScript definitions for your API responses, ensuring frontend and backend data structures are in sync.

How to Use the Converter

Convert your JSON to TypeScript in three simple steps:

  1. Paste Your JSON: Enter or paste your JSON data into the left input area. You can also start with our default example.
  2. Customize Options: Use the settings panel to define the root interface name, choose between an `interface` or `type` alias, and toggle semicolons or comments.
  3. Generate & Copy: Click the “Convert” button (or just wait for the real-time conversion) and use the “Copy” button to grab your new TypeScript interface.

Use the “Format JSON” button to automatically prettify your JSON input, making it easier to read and debug before conversion.

Frequently Asked Questions

Interfaces are primarily used for defining object shapes and can be extended or implemented. Type aliases can represent any type, including primitives, unions, and tuples. For object-like structures from JSON, both work well. Interfaces are generally preferred for object shapes as they are more extensible, while type aliases are better for complex type compositions.

Nested objects are converted to inline interfaces by default. For example, an `address` property containing `street`, `city`, and `zip` would become an inline object type within the main interface. This approach maintains the structure of your JSON data directly in the TypeScript format.

Yes! The converter properly handles arrays. It inspects the array elements to infer their type. If all elements have a consistent structure, it will generate a typed array (e.g., Address[]). If elements are mixed, it will fall back to a more general type like any[].

Absolutely. All conversion logic runs entirely within your web browser using JavaScript. Your JSON data never leaves your computer and is not sent to any server. This ensures complete privacy and security for sensitive data.

The converter supports standard JSON format as defined by RFC 8259. This includes objects (`{}`), arrays (`[]`), strings, numbers, booleans (`true`/`false`), and `null`. The tool is designed to automatically handle deeply nested structures and complex data combinations.

Understanding JSON and TypeScript

To fully appreciate the power of this tool, it’s helpful to understand the two technologies at its core. Our converter bridges the gap between the data-interchange format of JSON and the statically-typed world of TypeScript.

What is JSON?

JSON (JavaScript Object Notation) is a lightweight, text-based format for data interchange. It is easy for humans to read and write and easy for machines to parse and generate. Because of its simplicity and flexibility, it has become the de facto standard for data transmission in web APIs.

What is TypeScript?

TypeScript is a superset of JavaScript that adds static types. By providing type definitions for variables, functions, and objects, TypeScript allows developers to catch errors early in the development process. It enhances code quality, readability, and scalability, especially in large and complex projects.

Combining these two, our tool provides a seamless way to create a typed “schema” or “contract” from a sample JSON payload, ensuring that your TypeScript application correctly handles the data it receives.

Practical Use Cases for This Tool

API Integration

When working with a third-party REST or GraphQL API, paste a sample response to quickly generate the necessary types for your application’s data layer or state management.

Configuration Files

If your application uses JSON-based configuration files (e.g., `config.json`), you can generate interfaces to ensure that your code accesses configuration properties in a type-safe way.

Database & Mocks

Create types from sample database documents (like from MongoDB or Firestore) or generate interfaces for mock data used in unit tests and UI development.

Best Practices for Generated Interfaces

Our converter provides an excellent starting point, but you can often refine the output for better code quality. Here are some tips for working with the generated TypeScript:

  • Refine Optional Properties: If some fields in your JSON are not always present, manually add a `?` to the property name (e.g., `middleName?: string;`) to make it optional.
  • Use More Specific Types: The tool may infer a generic type like `string`. You can often make this more specific, for example, by using a union of literal types (e.g., `status: ‘pending’ | ‘completed’ | ‘failed’;`).
  • Extract Nested Interfaces: For deeply nested objects, consider extracting the generated inline types into their own named interfaces for better reusability and readability across your codebase.
  • Add Documentation: Use the “Generate JSDoc comments” option or manually add your own comments to describe what each property represents, especially if the keys are not self-explanatory.