The W3C Web Ontology Language (OWL) is a powerful knowledge representation\nformalism at the basis of many semantic-centric applications. Since its\nunrestricted usage makes reasoning undecidable already in case of very simple\ntasks, expressive yet decidable fragments have been identified. Among them, we\nfocus on OWL 2 RL, which offers a rich variety of semantic constructors, apart\nfrom supporting all RDFS datatypes. Although popular Web resources - such as\nDBpedia - fall in OWL 2 RL, only a few systems have been designed and\nimplemented for this fragment. None of them, however, fully satisfy all the\nfollowing desiderata: (i) being freely available and regularly maintained; (ii)\nsupporting query answering and SPARQL queries; (iii) properly applying the\nsameAs property without adopting the unique name assumption; (iv) dealing with\nconcrete datatypes. To fill the gap, we present DaRLing, a freely available\nDatalog rewriter for OWL 2 RL ontological reasoning under SPARQL queries. In\nparticular, we describe its architecture, the rewriting strategies it\nimplements, and the result of an experimental evaluation that demonstrates its\npractical applicability. This paper is under consideration in Theory and\nPractice of Logic Programming (TPLP).\n