Expat XML Parser

If you're looking for a fast and reliable way to handle XML in C, you should definitely check out Expat XML Parser. It's a lightweight, stream oriented library that's been around for ages and is trusted by some of the biggest names in open source software. You’ll find it powering parts of the Apache HTTP Server, Mozilla, PHP, and even Python so you know it’s battle tested.

What makes Expat stand out is its ability to handle massive XML files without loading everything into memory at once. Instead, it processes the document in chunks, which is perfect when you're dealing with files that are just too big to fit into RAM. You set up callback functions like telling the parser what to do when it encounters a start tag, an end tag, or text and it fires those events as it reads through the data. It might sound a bit technical at first, but you really only need to learn a handful of functions to get up and running.

Even though Expat isn’t officially a SAX parser, it works in a very similar way. In fact, many developers use it as the foundation for building their own SAX or DOM parsers. One of its coolest features is that you can pause and resume parsing whenever you want, which opens the door to more advanced use cases like pull parsing.

Licensed under the permissive MIT/X Consortium license, Expat is free to use, modify, and distribute. It’s efficient, flexible, and though it might take a minute to get comfortable with, it’s absolutely worth the effort if you need high performance XML parsing in C.