json-property-names

Requires direct properties of component schemas to use lower camelCase names.

Attribute	Value
Category	Schema
Maturity	Gold
OpenAPI	Swagger 2.0; OpenAPI 3.0, 3.1, 3.2
Starter	Off
Lenient–Complete	Error

Intent

One predictable JSON naming convention reduces client-side renaming and inconsistent payloads.

Flags

A direct property under components.schemas.*.properties unless its name starts with a lowercase letter and then contains only letters or digits.

Does not flag

Names such as createdAt and line2. Nested properties and properties outside component schemas are outside this rule's scope.

See it fail

components:
  schemas:
    Payment:
      type: object
      properties:
        created_at:
          type: string

Diagnostic: JSON property names should use camelCase.

Fix it

components:
  schemas:
    Payment:
      type: object
      properties:
        createdAt:
          type: string

Changing a published property name is an API compatibility change; coordinate the migration with consumers.

Configure

profiles:
  default:
    rules:
      extends: [recommended]
      override:
        json-property-names: warn

Nearby: schema-definition-camel-case.