There are innumerous technology choices when developing a web app. Though I lean towards what I know when developing, those choices are still wide. For example, if you have a lot of unstructured data coming from APIs you may be well served with a NoSQL database like MongoDB. If you have known structured data, a relational database such as MySQL can be a strength. Or maybe you need to get off the ground quickly and something like Firebase will suffice. A few other architecture choices that commonly have to be made include hosting, design frameworks, and language/transpilation choices...
Whoever wrote it, I can look over code and provide feedback on how we might improve it. A few examples include adopting a style standard, adding unit tests, or re-architecting sub components...
I can add credit card, ACH, and other financial functionality to your web app through APIs like Stripe.