curl --request GET \
  --url https://macrobymark.com/api/indicators/search \
  --header 'X-API-Key: <api-key>'

{
  "results": [
    {
      "slug": "<string>",
      "name": "<string>",
      "source": "<string>",
      "sourceId": "<string>",
      "category": "<string>",
      "frequency": "<string>",
      "unit": "<string>"
    }
  ],
  "total": 123
}