openapi.json is the official App Store Connect OpenAPI 3 specification (v4.3), downloaded from:
https://developer.apple.com/sample-code/app-store-connect/app-store-connect-openapi-specification.zip
To update:
curl -L -o /tmp/asc-spec.zip https://developer.apple.com/sample-code/app-store-connect/app-store-connect-openapi-specification.zip
unzip -p /tmp/asc-spec.zip openapi.oas.json > api-spec/openapi.jsonLast downloaded: 2026-03-27 (v4.3)