cf.json

// GET /people/2.json
{
  "id": 2,
  "first_name": "Captain",
  "email": "CaptainCrunch@nerdyworm.com"
  "last_name": "Crunch",
  "custom_fields": {
    "abilities": [
      "sugar_rush"
    ],
    "hit_points": 100,
    "boss_type": "double_question_mark"
  }
  // ...
}

// GET /custom_field_labels.json
[
  {
    "id": 1
    "name": "Abilities",
    "kind": "array",
    "key": "abilities",
    "values": [
      "sugar_rush",
      "fireball"
    ]
  },
  {
    "id": 2,
    "name": "Hit Points",
    "key": "hit_points",
    "kind": "integer"
  },
  {
    "id": 3,
    "name": "Boss Type",
    "key": "boss_type",
    "kind": "string",
    "values": [
      "big",
      "super_big",
      "double_question_mark"
    ]
  },
  // ...
]

// GET /custom_field_labels/1/values.json
[
  {
    "id": 1,
    "name": "Sugar Rush",
    "key": "sugar_rush",
    "custom_field_label_id": 1,
  },
  {
    "id": 2,
    "name": "Splodie",
    "key": "splodie",
    "custom_field_label_id": 1,
  }
  // ...
]