Another type of integration tests are called contract tests. These are the ones that verify cross-system integration. You should have lots of them and they are also essential! I can highly recommend https://pactflow.io/. Source: about 1 year ago

Your actual front-end application could be a fetch and a JQuery library. But you need probably want to choose a framework to handle user logins -- more work than it sounds like -- login, forget password, login with google, login with twitter/facebook, email setup... etc. etc. I was going to look into userfront for most of this work for my thing -- https://userfront.com/. Source: over 1 year ago

I researched and tried several hosted auth solutions. I ended up choosing https://userfront.com/ I think it has the best DX. - Source: Hacker News / almost 2 years ago

Would something like https://userfront.com/ fit you? Source: almost 3 years ago

In this article, I describe a simple approach we use at Userfront to make our tests easier to write and less prone to error. - Source: dev.to / almost 3 years ago

Adding authentication and access control to your React application doesn't have to be a hassle. Both the setup step and, more importantly, the maintenance over time, are handled with modern platforms like Userfront. - Source: dev.to / about 3 years ago