TypeScript: Type Vs Interface

Explains how to choose between type and interface in TypeScript.


When working with TypeScript, understanding the nuances between type and interface is crucial. Both constructs offer ways to define shapes or structures, but they have some distinctions in their use cases.


The type keyword in TypeScript allows you to create aliases for existing types, making it easier to reuse and reference complex types.

type Point = {
  x: number;
  y: number;
// Usage
const coordinates: Point = { x: 10, y: 20 };

Use Cases:

  • Creating union types.
  • Defining complex types and intersections.

Key Points:

  • Flexible and powerful for creating custom types.
  • Supports union types and intersections.
  • Can be used with primitive types, objects, and function types.


The interface keyword is another way to define custom types in TypeScript, especially suited for declaring the structure of objects.

interface Point {
  x: number;
  y: number;
// Usage
const coordinates: Point = { x: 10, y: 20 };

Use Cases:

  • Declaring the shape of objects and their properties.

Key Points:

  • Primarily used for defining object shapes.
  • Supports extending and implementing other interfaces.
  • Can be augmented to add new properties later.

When to Use Which?

Use type When:

  • Creating unions or intersections of types.
  • Defining complex and reusable types.
  • Working with primitive types and function types.

Use interface When:

  • Describing the shape of objects.
  • Extending or implementing other interfaces.
  • Augmenting existing declarations.


Both type and interface play essential roles in TypeScript, offering developers flexibility and clarity when defining custom types. Understanding their strengths and best use cases empowers developers to choose the right tool for the job.

Remember, in many scenarios, the choice between type and interface is a matter of personal or team preference. Consistency within a codebase is often more important than the specific choice between the two.