Abstract
The RDF Mapping Language has seen various extensions over the years and was overhauled and modularized by
the W3C KGC Community Group. However, this variety of RML versions and varying feature support by
different mapping engines makes it hard for users to know how to create valid mapping rules. We demonstrate
RML Playground: a Web application that guides users to edit, validate, and execute mapping rules for
configurable RML versions and mapping engines. The RML Playground offers a text editor with real-time RDF
syntax and SHACL shape validation and autocompletion, powered by the Semantic Web Language Server; a
knowledge graph construction pipeline using a configurable mapping engine; and curated example mapping
rules illustrating the targeted RML version. RML Playground currently has two deployed instances: the latest
KGC Community RML version with Burp as mapping engine, and the RML.io-published RML version with
RMLMapper as mapping engine. Completely automated using the specifications' ontology and shape
descriptions, the RML Playground is easily extensible and maintainable to new RML versions and extensions.