С помощью утилиты jq.

Установка в windows с помощью chocolatey

choco i -y jq

Форматирование json

echo '{"foo": "lorem", "bar": "ipsum"}' | jq

# или

echo '{"foo": "lorem", "bar": "ipsum"}' | jq '.'

Результат

{
  "foo": "lorem",
  "bar": "ipsum"
}

Или можно натравить на curl запрос

curl -sSL -X GET "https://httpbin.org/json" -H "accept: application/json" | jq

{
  "slideshow": {
    "author": "Yours Truly",
    "date": "date of publication",
    "slides": [
      {
        "title": "Wake up to WonderWidgets!",
        "type": "all"
      },
      {
        "items": [
          "Why <em>WonderWidgets</em> are great",
          "Who <em>buys</em> WonderWidgets"
        ],
        "title": "Overview",
        "type": "all"
      }
    ],
    "title": "Sample Slide Show"
  }
}

Преобразование [{ "a": "a" }, { "b": "b" }] в { "a": "a", "b": "b" }

echo '[{ "a": "a" }, { "b": "b" }]' | jq add