Json: :Parsererror (784: Unexpected Token at '{)

What is wrong with my JSON? I am running on Rails 6, and I am loading the file contents, after I load the file, I try to parse it. However, I am running into parsing errors.

This is my code:

    file_name = File.join(Rails.root, "lib", "data", "cars.json")
    file_content = File.read(file_name)
    json_plans = JSON.parse file_content

Error:

JSON::ParserError (784: unexpected token at '{)

JSON:

{
  "first_car": {
    name: "first car",
    plans:
      [
        {
          "amount": 0,
          "stripe_id": "" ,
          "name": "first car", 
          "published": true,
          "interval": "year",
          "interval_count": "1",
          "category": "car",
          "slug": "first_car"
        }
      ]
  },
  "second_car": {
    name: "second car",
    plans:
      [
        {
          "amount": 1000,
          "stripe_id": "",
          "name": "second car",
          "published": true,
          "interval": "year",
          "interval_count": "1",
          "category": "car",
          "slug": "second_car"
        }
      ]
  },
  "third_car": {
    name: "third car",
    plans:
      [
        {
          "amount": 20000,
          "stripe_id": "",
          "name": "third car",
          "published": true,
          "interval": "year",
          "interval_count": "1",
          "category": "car",
          "slug": "third_car"
        } 
      ]
  }
}