I have multiple about:profiles on Firefox, each with different accounts (think school vs personal vs work etc.) Works quite well.

Firefox multi-account containers, no?

PortableApps makes this especially easy. Nothing ever touches your main system files, each instance of the browser is quarantined to its own folder.

Why not use the built-in profile functionality?

God knows if Google does any kind of cross-correlation between them. I would actually expect it.

They are also part of the Chromium project, so you're welcome to check it out, inspect the source code, and build it locally.

Just because it's open doesn't mean anyone can do such thing. I'm a professional dev and I can't browse such a complex C++ codebase.

I was being flippant, but isn't that true of anything though? How do you know Linux isn't secretly reporting all your activities to Big Penguin?

You should be able to trust a popular open-source project, because you trust that there are folks who will go in and take a sticky beak at these kinds of things. This why a lot of security folks prefer open-source software over close-sourced solutions.

Surely, if Chromium were cross-correlating profiles, then it'd be on the front page of Hacker News in short order.

IME they do cross-correlate...

can you use them in parallel? in any case i don't want any correlation between the two (other than the IP i guess). in my case i often log in to the same website from different accounts for testing purposes

You can you them in parallel and they share no extensions, sessions, website settings, or other local data. You can even have separate themes for each profile.

I'm unaware of any potential problems relating to fingerprinting and so on, but for your use case it doesn't sound like it'd be a problem.