There is no single alternative to XML, and I don't want to say that all XML is bad. But it's very commonly misused, because someone, somewhere tried to solve the wrong problem and XML happened to be the "default" solution. So, really, the alternatives depend heavily on the context.
What I've seen personally often involved overly complex SOAP/WSDL services for things that could be accomplished with a simple HTTP request. Look at query prams, return the correct HTTP code and you're done.
Another common pathology is problem over-solving. Instead of writing a library to solve some problem and providing a sensible API, people write the library, hide it, then write an XML "driver" that consumes a custom-designed language encoded via XML tags. The alternative in this case is simply providing the original API.