I have read through SharePoint 2013 documentations (https://msdn.microsoft.com/en-us/library/office/dn790706.aspx) on how to authorize SharePoint Add-ins. We want to avoid using a high trust app since our product is primarily Java-based. We looked into using a low trust app but documentations state that this requires Azure or Office 365 which our customer does not have.
Is it possible to develop a low trust app without Azure or Office365? Is the high-trust app the only approach?