Earlier quoted context omitted.
No, I won't beat them. But if it a limited subset that I can implement with twenty lines straightforward code, that will often be cheaper. I've been on projects where they imported xml-parsers many times bigger than the rest of the whole codebase just to send a well formatted order number.
xml and json are different beasts A json parser can probably be implemented in an afternoon. But a conformant xml parser can take months. There are some weird things in xml, for example, this is correct xml: ]] ]>>?>]> >?> And for external entities, you need an http client in the xml parser, although it is probably better to not support that part of the standard.
And we didn’t need a conformant xml parser, which I know is huge and complex.