Advanced JSON to TypeScript

Type Safety Without the Typing: The Ultimate JSON Converter

TypeScript is the standard for modern web development, but manually writing Interfaces for massive API responses is tedious and error-prone. Our Advanced JSON to TypeScript Converter automates this workflow. Simply paste a raw JSON object—whether it's from a database dump, a REST API, or a config file—and instantly generate robust, clean TypeScript Interfaces or Types. This tool is specifically designed to handle complex, nested structures and array variations.

Feature Highlight: Smart Array Analysis

Most converters only look at the first item in an array to generate the type. This is dangerous. If the first user has a "phone" field but the second user doesn't, a basic converter will mark "phone" as required, causing runtime errors later. Our Smart Analysis algorithm scans the entire dataset:

• Detection: It compares every object in an array.
• Resolution: If a field is missing in some objects, it automatically marks that property as optional (`?`).
• Union Types: If a field is a string in one object and a number in another, it generates a union type (`string | number`).

Flattened vs. Nested Interfaces

Clean code is subjective, so we offer two output styles:

• Flatten (Recommended): Extracts nested objects into their own named interfaces (e.g., `interface Address {...}`). This promotes reusability and keeps your code readable.
• Nested: Keeps everything inline within the Root object. Better for quick copy-pasting of small, one-off types.

Frequently Asked Questions

Should I use Interface or Type?

This tool generates Interfaces by default because they are generally faster for the TypeScript compiler to process and support "Merging" (declaration merging). However, for simple data structures, they are functionally identical to Types.

How does it handle Null values?

If the input JSON contains `null`, the converter cannot know the true type. It will typically type it as `any` or `null`. We recommend manually reviewing fields typed as `any` after generation to ensure strict safety.

Can I paste a huge API response?

Yes. The processing happens locally in your browser. You can paste a 5MB JSON file with thousands of lines, and it will generate the types in milliseconds without sending your data to any server.