JsonToTypescript

JSON → TypeScript Model CLI

Convert raw JSON into clean, readable TypeScript types or interfaces in seconds.

Features

• One-step generation: paste JSON and press Enter to generate a .ts file.
• Readable names: nested types are named from JSON keys
  e.g. profile → Profile, projects → Project[], settings.notifications → Notifications.
• Smart inference
  • null becomes any (and any dominates unions).
  • ISO-like date strings become string | Date.
  • Arrays of short token-like strings become string-literal unions, e.g. ("admin" | "editor")[].
• File naming: output file uses the model name lowercased, e.g. User → user.ts.
• No dependencies: single-file Node CLI.

Install

npm install -g json-to-typescript

Usage

Interactive (paste JSON)

json-to-typescript
# Prompts:
# Model name (e.g., User, OrderItem): User
# Paste JSON and press Enter when done:
# { ...your JSON... }
# => generates user.ts in the current directory

From a file

json-to-typescript --model-name Order --input-json ./order.json

With options

• --interface → generate interface instead of type
• --no-dates → don't convert ISO strings to Date
• --no-color → plain log output
• --out path.ts → specify output file path

Example

Input JSON:

{
  "id": 123,
  "name": "Patrick",
  "profile": { "bio": "Dev", "age": 30 },
  "tags": ["typescript", "node"]
}

Output:

export type Profile = {
  age: number;
  bio: string;
};

export type User = {
  id: number;
  name: string;
  profile: Profile;
  tags: ("typescript" | "node")[];
};

Contributing

PRs welcome!

Future Enhancements

• Nested file output → split models into multiple .ts files instead of one big file
• JSON → Java
  • Generate POJOs with optional Lombok annotations.
• JSON → Rust
  • Generate structs with optional serde annotations for serialization.
• JSON → Python
  • Generate Pydantic models (ideal for FastAPI and modern Python backends).
• Java → TypeScript
  • Translate existing Java POJOs into matching TypeScript interfaces.
  • Config file support to specify which POJOs to include for translation.
• VS Code extension → right-click JSON → Generate TypeScript Interface
• Web playground → paste JSON in browser → copy TS interface

License

MIT © Kevin Gleeson