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. The recommended parser is the Apache version of Xerces (though the reliability problems with the parser that comes with the JDK seem to have been resolved in Java 8). By default Saxon uses the parser that comes with the Java platform. 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.