curl --request GET \
  --url https://{tenant}/api/apis/{apiId} \
  --header 'Authorization: Bearer <token>'

{
  "api_definition": {
    "api_id": "b84fe1a04e5648927971c0557971565c",
    "auth": {
      "auth_header_name": "authorization"
    },
    "definition": {
      "key": "version",
      "location": "header"
    },
    "id": "66596520c7f5720001b22558",
    "name": "Tyk Test API",
    "org_id": "664a14650619d40001f1f00f",
    "proxy": {
      "listen_path": "/tyk-api-test/",
      "strip_listen_path": true,
      "target_url": "https://httpbin.org"
    },
    "use_oauth2": true,
    "version_data": {
      "not_versioned": true,
      "versions": {
        "Default": {
          "name": "Default"
        }
      }
    }
  }
}