In March 2013, the W3C recommended SPARQL 1.1 to retrieve and manipulate decentralized RDF data. Real-world usage requires advanced features of SPARQL 1.1. recommendations As these are not consistently implemented, we propose a test framework named TFT (Tests for Triple stores) to test the interoperability of the SPARQL end-point of RDF database systems. This framework can execute the W3C's SPARQL 1.1 test suite and also its own tests of interoperability. To help the developers and end-users of RDF databases, we perform daily tests on Jena-Fuseki, Marmotta-KiWistore, 4Store and three other commercial databases. With these tests, we have built a scoring system named SPARQLScore and share our results on the website http://sparqlscore.com.