I've been looking at putting together a prototype for years, and have evaluated a ton of platforms. I wanted something that was flexible, had a design framework I could work with, not create from scratch, didn't license per-user and gave freedom to really build a powerful application. After 6 months of using WeWeb, I can confidently say that I have finally found what I'm looking for.
Before WeWeb I had been down the route with Mendix (Powerful, High Learning Curve, Expensive Per-Seat Pricing), Bubble (Tried to force myself to use it, powerful, but everything is DIY, including design which is incredibly difficult), Adalo (Interesting, but really mobile first) and many others.
WeWeb is unique, it offers a decoupled Front End and Back End. WeWeb provides a very powerful Front End that is easy to configure, yet can be made to do just about anything. There is an easy to use design framework that you can work within, or customize to your heart's content. On the Back End they offer integration with a number of providers, in my case I'm using Xano which I also absolutely love.
If you are looking at putting together a powerful web application, and applications like Mendix or Bubble is on your list, then I highly suggest you take a look at WeWeb, so far there is nothing I have not been able to do in the platform, that I know you can do in those environments. To me, WeWeb is the Bubble killer many of us have been waiting for.