@Bene's "sparql" tool used to be available at https://tools.wmflabs.org/bene/sparql/, but it's currently down. In addition, the source doesn't seem to be available in any public repository. It should be revived or taken over by new maintainers.
Note: This task was part of the "Improving Visual SPARQL Query builders" project, carried out during the Wikimedia Hackathon 2019. Project poster: