How JSON maps to TypeScript
| JSON value | TypeScript type |
|---|---|
"hello" | string |
42 / 3.14 | number |
true / false | boolean |
null | null |
["a", "b"] | string[] |
[1, "x"] | (number | string)[] |
| Nested object | Named interface |
Example
JSON input:
{ "id": 1, "name": "Alice", "tags": ["admin"] }
Generated TypeScript:
interface Root {
id: number;
name: string;
tags: string[];
}
Use the generated interfaces in your TypeScript project for type checking and IDE autocomplete. Paste the output directly into a .ts file.
Frequently Asked Questions
How does JSON to TypeScript conversion work?
The tool walks the JSON structure recursively. Each JSON object becomes a TypeScript interface. String values become string, numbers become number, booleans become boolean, null becomes null, arrays become type[], and nested objects become named interfaces derived from the key name.
How are interface names generated?
Interface names are derived from the JSON key using PascalCase conversion. The root object always becomes Root. A key named userAddress becomes UserAddress, and user_profile becomes UserProfile. Array item interfaces use the singularized key name — so a key books generates a Book interface.
Can I use the generated interfaces directly?
Yes. Copy the output and paste it into any .ts file. The interfaces are standard TypeScript and work immediately with your TypeScript compiler, VS Code IntelliSense, and other TypeScript-aware IDEs.
Is my JSON data sent to a server?
No. All TypeScript generation runs entirely in your browser using JavaScript. Your JSON data never leaves your device.