I need a browser that allows me to run multiple tabs or instances, but I need that each page is completely isolated.
So I should be able to use a different proxy on each page and separate cookie store and cache.
Software Recommendations Stack Exchange is a question and answer site for people seeking specific software recommendations. It only takes a minute to sign up.Sign up to join this community
Oni, Ghost Browser lets you isolate browsing Sessions in each tab. You can also assign a different proxy for each tab with new Ghost Proxy Control extension. No messing VMs or anything. Everything is right there in one browser window. More details here: https://ghostbrowser.com/blog/set-different-proxy-for-each-tab/
Somiibo is another software that does this as well. You can assign a unique session to each tab which means independent proxies, logins, cache, cookies, and everything. This proxy browser is free at the moment.
Thinking out of the box and back in the best that I know of is to use Virtual Box or VMWare to run multiple operating system instances, each with a browser running, possibly "full screen", in tabs.