I am curious as to what is the standard nowadays for building APIs in terms of formatting the POST input parameters : json vs x-www-form-urlencoded ? Any pros and cons ? Does AWS lambda + SST influence on that choice ? I'm hesitant going one way vs the other...

Maybe it's because we're very much in the nodejs camp when it comes to the backend but submitting json makes it easier to work with

I think the format of an API should be consumer led. E.g, you want to enter a market that conventionally uses XML, then use XML. All APIs I have integrated in the last two years have been Rest JSON API or graphql 👍

Funnily enough, we've recently had to deal with some XML/SOAP from a 3rd party API recently, bloody awful!

FYI, I'm going for the JSON route, it indeed makes everyone's life easier

XML is still so common, at least among our clients 😭