Programatically fetching your quota/active utilization, etc. from Wasabi (wasabi.com) is pretty straightforward with their API.
1) Create a user at https://console.wasabisys.com/users with API-access
2) Create access keys for new subuser and assign permissions via policies. My user has the following policies assigned: WasabiReadOnlyAccess, WasabiViewAuditLogs, WasabiViewBillingAccess and WasabiViewEventNotifications
Query their API like so:
curl -H "Authorization: ACCESS-KEY:SECRET-KEY" https://billing.wasabisys.com/utilization
Note that no type of Authorization is set, no "Basic", "Digest", etc.
Getting this via jQuery is trivial, I've written a simple script for it you can try out.
Replace ACCESS-KEY and SECRETKEY on line 7 with your credentials.