libxml2

libxml2 is a software library written in C that provides parsing, creation, and manipulation of XML documents. It exposes a DOM-like in-memory tree as well as streaming interfaces (SAX) and a robust XPath engine for querying. The library is widely used by applications and other libraries as a core XML processor.

Core capabilities include parsing of XML 1.0 and XML 1.1 documents, namespace processing, validation against DTDs, and extended validation options via Relax NG and XML Schema in optional components. It supports XInclude, XML Catalogs, and incremental parsing for large documents. The API covers DOM-style access through xmlDocPtr and xmlNodePtr as well as event-driven parsing and push parsing.

Portability and performance are emphasized. libxml2 runs on a broad range of operating systems and compilers, and provides a clean C API suitable for embedding in other software. Bindings exist for many languages, allowing use from Python, PHP, Perl, Java, and others.

Licensing and history: libxml2 is released under a permissive MIT/X Consortium-style license. It was developed by Daniel Veillard in the late 1990s and has been maintained as a core project in the XML ecosystem, often used in conjunction with related libraries such as libxslt for XSLT processing.