JSON files

Manifest:
{
    "format_version": 1,
    "header": {
        "name": "(Skinpack Name)",
        "uuid": "(UUID 1)",
        "version": [0, 0, 1]
    },
    "modules": [
        {
            "type": "skin_pack",
            "uuid": "(UUID 2)",
            "version": [0, 0, 1]
        }
    ]
}

Skins:
{
  "geometry": "skinpacks/skins.json",
  "skins": [
    {
      "localization_name": "(Abbreviate Skin Name)",
      "geometry": "geometry.humanoid.custom",
      "texture": "(Skin File).png",
      "type": "free"
    },
    {
      "localization_name": "(Abbreviate Skin Name)",
      "geometry": "geometry.humanoid.custom",
      "texture": "(Skin File).png",
      "type": "free"
    }
  ],
  "serialize_name": "(Skinpack Name)",
  "localization_name": "(Abbreviate Skinpack Name)"
}