We are moving according to our roadmap of rolling out the product to more people. Since most people in the beta queue use Zendesk, this will be the first one to fully support before making sure Inbill works with other helpdesks.
Our Chrome extension should work anywhere but we will create dedicated apps for all helpdesks that we plan to officially support.
For now, Zendesk users rejoice! Your beta start is going to be expedited!