Ну судя по вот этому, он почему-то не устанавливает Header-ы
{success: 0, error: "api key not specified"} error: "api key not specified" success: 0
Failed to load https://wex.nz/tapi: Response to preflight request doesn't pass access control check:
No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access.
глянь в сторону
https://github.com/arvitaly/btc-e3