When developers ask for a serialization format other than what you're providing, it's generally because they're using a particular language that has a parser th

When developers ask for a serialization format other than what you're providing, it's generally because they're using a particular language that has a parser they like (or is the only parser they're aware of) for that particular serialization format. Moreover, the language they're using might be dictated by their employer and not by personal choice. A combination of those reasons is why SOAP and XML have lived on for so long. What you should derive from this, however, is not that you need to provide better support for that particular serialization format; rather, if you want to make this particular set of developers happier, you need to provide better support for that language they're using. In general, this means building SDKs for your API in whatever language your developers prefer. When given the choice between building an integration with an XML API from scratch, building an integration with JSON API from scratch, and building an integration with an SDK that does most of the work for you, developers will generally pick the last option, regardless of how the data is being serialized underneath.