content-type-response

Requires Content-Type on successful responses that declare response content.

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

Intent

Clients should receive an explicit media type for every successful response body.

Flags

A response whose code begins with 2, except 204, when it declares content but no Content-Type response header. Header matching is case-insensitive.

Does not flag

Responses without content, 204, non-2xx responses, or responses that define Content-Type.

See it fail

responses:
  '200':
    description: OK
    content:
      application/json:
        schema:
          type: object

Diagnostic: Successful responses with body should define `Content-Type` header.

Fix it

responses:
  '200':
    description: OK
    headers:
      Content-Type:
        schema:
          type: string
          enum: [application/json]
    content:
      application/json:
        schema:
          type: object

Configure

profiles:
  default:
    rules:
      extends: [recommended]
      override:
        content-type-response: error

Nearby: header-required-for-content-type-response, 204-no-content-type.