https://www.rainforestqa.com/careers/
We have plenty of interesting technical challenges and we care a lot about company culture (you can see our CEO talk about it here https://lattice.com/resources-for-humans/fred-stevens-smith-...). We've been remote-first on the engineering side since the early days and most of our engineers are distributed all over the world including the Americas, Europe, Asia and Africa. We fly everyone to SF for face-to-face meetings a couple of times per year.
We're working with a bunch of cool tech from fraud detection, plain-old Random Forests, to using CNNs to visually understand websites, to managing thousands of testers using thousands of freshly-provisioned VMs, to provisioning real mobile devices for app testing. You can see a short talk I gave about one of our older projects here: https://www.youtube.com/watch?v=7_h8PElXio8.
I'd be happy to answer any questions you might have :)