AlfaBankExchange.el

(defvar alfa-currencies 'nil "Current value of currencies")

(defun alfa-currency-query ()
  "HTTP request to AlfaBank currency API"
  (let ((url "https://alfabank.ru/ext-json/0.2/exchange/cash/"))
    (web-http-get
     (lambda (httpc header my-data)
       (with-temp-buffer
	 (insert my-data)
	 (goto-char (point-min))
	 (let ((json-object-type 'plist))
	   (setf alfa-currencies (json-read)))))
     :url url)))

(cl-defun alfa-get-currency-exchange (&optional (currency "usd") (direction "sell"))
  "Get (sell buy) value for following currencies: usd eur gbp from Alfa-Bank.
   `currency' is currency code \"usd\", \"eur\"), `direction' is \"sell\" or \"buy\"."
  (plist-get
   (seq-find
    (lambda (elt)
      (string= (plist-get elt :type) direction))
    (plist-get
     (plist-get
      (plist-get alfa-currencies :response)
      :data)
     (intern (concat ":" currency)))) :value))