Is it true that the use of Castor XML mandates Xerces as XML parser?
Yes and no. It actually depends. When requiring pretty printing during marshalling, Castor will internally use Apache’s Xerces to implement this feature. As such, when not using this feature, Xerces is not a requirement, and any JAXP-compliant XML parser can be used (for unmarshalling). In other words, with the latter use case, you do not have to download (and use) Xerces separetely.