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