curl --request GET \
  --url https://tonapi.io/v2/nfts/collections

{
  "nft_collections": [
    {
      "address": "0:FD595F36B4C1535BEC8461490D38EBB9AE3C38DD6ACE17CA63ABE2C6608BE159",
      "next_item_index": 1,
      "raw_collection_content": "<string>",
      "approved_by": [
        "getgems"
      ],
      "metadata": {},
      "previews": [
        {
          "resolution": "100x100",
          "url": "https://site.com/pic1.jpg"
        }
      ]
    }
  ]
}