The following software must be installed separately, it is not included with the Saxon download.

By default Saxon uses an XML parser that supports the SAX2 interface. Saxon has been tested successfully in the past with a wide variety of such parsers including Ælfred, Xerces, Lark, SUN Project X, Crimson, Piccolo, Oracle XML, xerces, xml4j, and xp. In the past Saxonica recommended using the Apache version of Xerces in preference to the built-in parser delivered with the JDK, but since JDK 8 the built-in parser appears to be equally reliable. The parser must be SAX2-compliant. All the relevant JAR files must be installed on your Java CLASSPATH.

Saxon will also work with a StAX parser. Generally speaking, StAX parsers are less mature and less interoperable than SAX parsers, and any performance advantage is likely to be very minor. However, the support for StAX provides the ability to supply input via a customized pull pipeline. Saxon is tested with Woodstox 3.0.0. Saxon's schema validation is available only with a SAX2 parser.