Saxonica recently released Saxon/C as a beta release of Saxon-HE on the C/C++ programming platform. APIs are offered currently to run XSLT 2.0 and XQuery 1.0 from C/C++ or PHP applications. Saxon/C is built from the Java product Saxon-HE 9.5.1.5 using the Excelsior JET tool [version 9.0 (MP2)]. The current release is Saxon-HE/C 0.3.1.
Follow the instructions to set up a server on DigitalOcean: