Custom Web Browser with user permissions + proxy support

Overview We need a custom browser-type application that will allow us to be logged into a specific site using different accounts, in separate tabs--with each tab/connection using a different proxy connection. The will be two different sites this browser should be able to support, with the possibility of more being at a later point. Features - There will be a login/password required for the app with two different user roles: Admin, and User. - The Admin role will be able to set username/password for each account, along with the defined proxy to be used. - The User role will have restricted access. They will not be able to change any settings i.e. creating new accounts, setting username/password, proxy etc. - The User role will also have to be restricted from navigating to specific pages in each of the tab/connection pages (these pages will be defined by the Admin) - The app should be able to log into multiple accounts at the same time--using a different session + ip for each new tab - There should be a notes tab that can be saved for future use Ideally I would like this application to work on both MAC and PC.. but at the very least it needs to work on either MAC or PC.