Saxon is an XSLT and XQuery processor created by Michael Kay and now developed and maintained by the company he founded, Saxonica.
The SaxonCS product is built from the Java source base by means of a custom Java-to-C# transpiler written in XSLT (see [1] Archived 2022-06-10 at the Wayback Machine).
Saxon-B was open-source software released under the Mozilla Public License, while Saxon-SA was a closed-source commercial product.
Saxon offers strict conformance to the XSLT 2.0, XPath 2.0 and 3.0, and XQuery 1.0 and 3.0 W3C Recommendations, and also implements XML Schema 1.0 and 1.1.
In 2012, following a series of prototypes, Saxonica released Saxon Client Edition (Saxon-CE), a version of the product adapted to run within the browser environment.
Saxon-CE provides the first implementation of XSLT 2.0 running on the browser, and also extends the language so that rather than merely generating HTML, it can directly handle user interaction.
In February 2016 Michael Kay announced that Saxonica was working on a replacement for Saxon-CE written in pure JavaScript, and dubbed Saxon-JS.
The Saxon versions that are available for the Java, C (including PHP and Python), and .NET platforms are built from a single codebase.
It provides basic XSLT 3.0, XPath 3.1, and XQuery 3.1 functionality, as defined by the respective specifications.
Previously the open-source XSLT processor Saxon-CE was cross-compiled from the common Java source using GWT.
In contrast to Saxon-HE and the discontinued Saxon-CE, SaxonJS is not open source, but it can be used for free in the browser or in Node.js.