This issue may be related to Cloudflare:

https://support.cloudflare.com/hc/en-us/articles/200169226-Why-am-I-getting-a-403-error-

NOTE: Kraken has the "Browser Integrity Check" enabled.

This may occur if your request contains suspicious headers. For example, your request may be missing a user agent, or use a non-standard user agent; so please check your request headers.

If you're unable to create any standard requests that our system permits, send us a full copy of the request(s) that you're attempting, including your IP address and all headers. This information would allow us to investigate further.