How to generate json?

Question

PHP

Please tell me how to generate this json

{
  "exchanges": {
    "from": {
      "P24UAH": {
        "to": {
          "PMUSD": {
            "in": 26.3703,
            "amount": 3524.3,
            "in_min_amount": 270,
            "in_fee": [
              "%",
              2
            ]
          }
        }
      }
    }
  }
}