no-duplicated-enum-values

August 4, 2026 · View on GitHub

Requires all values in an enum to be unique.

OASCompatibility
2.0✅
3.0✅
3.1✅
3.2✅
AsyncAPICompatibility
2.6✅
3.0✅
ArazzoCompatibility
1.0✅

API design principles

A duplicated value in an enum is always a mistake: it adds noise for readers, and some tools reject such schemas because JSON Schema requires enum values to be unique. This rule catches copy-paste errors early in your API definition.

Configuration

OptionTypeDescription
severitystringPossible values: off, warn, error. Default is warn in the recommended configuration.

Example configuration:

rules:
  no-duplicated-enum-values: error

Examples

Example of incorrect enum values (duplicated value red):

schemas:
  Color:
    type: string
    enum:
      - red
      - green
      - red

Example of correct enum values (all values are unique):

schemas:
  Color:
    type: string
    enum:
      - red
      - green

Resources