curl --request POST \
  --url https://api.iotools.cloud/v1/tool/json-key-extractor \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "input": "{\"user\":{\"id\":1,\"name\":\"Ada\"},\"items\":[{\"sku\":\"A1\",\"name\":\"Widget\"},{\"sku\":\"A2\"}]}",
  "mode": "name"
}
'

{
  "tool": "json-key-extractor",
  "tool_version": "1.0.1",
  "outputs": {
    "keys": [
      {
        "rank": "1",
        "key": "name",
        "count": "2"
      },
      {
        "rank": "2",
        "key": "sku",
        "count": "2"
      },
      {
        "rank": "3",
        "key": "id",
        "count": "1"
      },
      {
        "rank": "4",
        "key": "items",
        "count": "1"
      },
      {
        "rank": "5",
        "key": "user",
        "count": "1"
      }
    ]
  },
  "credits_used": 3,
  "credits_remaining": null
}