May 22, 2026

API Explorer now returns JSON for v2 REST endpoints

Thanks to user feedback, REST /v2/ endpoints in the API Explorer now return JSON responses instead of XML, matching the Accept: application/json header advertised in the request.

  • Path-level header parameters now inherit correctly — operations defined under a path in the OpenAPI specs pick up Accept and other header parameters declared at the path level, so v2 responses render as JSON in the Explorer.
  • No spec changes required on our side — the fix landed in the Fern platform; existing v2 specs render correctly without edits.

For an example, try List Customers (v2) in the API Explorer.