What are GraphQL scalars?

Scalars are the primitive data types in GraphQL, and they represent leaf values. A scalar field has no sub-fields to select, so the query stops there. Scalars also type arguments and variables.

The five built-in scalars are:

• String: a UTF-8 character sequence.
• Int: a 32-bit signed integer.
• Float: a double-precision floating-point number.
• Boolean: true or false.
• ID: a unique identifier. It is serialized like a String and often used as a cache key.

You can also define custom scalars such as Date or Email, and the server supplies the code that serializes, parses and validates them. @specifiedBy can link one to its format specification.

scalar Date
scalar Email
scalar URL

type User {
  id: ID!
  email: Email!
  birthDate: Date
}