YAML to TypeScript Converter

About this tool

Paste a YAML sample and get TypeScript type definitions you can use immediately. Emits `interface` declarations. Optional fields use `?`, so `strictNullChecks` will catch the ones your API omits.

When you would use it

• Typing an API client or validating a response shape at the boundary
• Bootstrapping models from a real YAML response instead of writing them by hand
• Keeping types in step with an API that has changed

Worked example

id: 4815
name: Ada Lovelace
active: true
score: 91.5
roles:
  - admin
  - editor
address:
  city: London
  postcode: NW1

export interface Root {
  id: number;
  name: string;
  active: boolean;
  score: number;
  roles: string[];
  address: Address;
}
export interface Address {
  city: string;
  postcode: string;
}

Things worth knowing

• Every object in an array is merged when inferring the shape, so a field missing from one item is marked optional rather than assumed to always be present.
• Identical nested shapes are de-duplicated into a single type instead of generating near-duplicates.
• Array element types are named from the singular of the field name, so posts produces a Post type.
• YAML resolves unquoted scalars to types, so no becomes a boolean and 1.10 becomes a number. Quote values you want treated as text.