First of all thanks for sharing all your insights on this blog. I regularly try to come back to your blog and I helped me grow as a QA Engineer quite a lot.
Could you help me and point me in the right direction?
You can write synchronous tests (like using Watir/Ruby) against asynchronous web interfaces, you just need to use the waiting/polling mechanisms (or write/extend your own) – the same as you need to do in asynchronous test automation tools.
I have tried to use cypress.io but the way it controls sites (through proxies) has (current) limitations like not working on iFrames and cross-domains which are deal-breakers for our end-to-end testing needs at present.
I’m glad I’ve been able to help you grow over the years.