Since its publication in 2001, the Common European Framework of Reference for Languages (CEFR) has gained a leading role as an instrument of reference for the teaching and certification of languages and for the development of curricula. At the same time, there is a growing concern that the CEFR reference levels have not been sufficiently illustrated, leaving practitioners such as teachers, test and curriculum developers, and textbook authors without comprehensive empirical characterizations of the relevant distinctions. This is particularly the case for languages other than English, where supplementary empirical tools are urgently needed. MERLIN addresses this demand for Czech, German and Italian and proposes a didactically motivated online platform that enables CEFR users to explore authentic written learner productions which have been related to CEFR in a methodologically sophisticated way. A cross-linguistic and multifunctional web-based interface will illustrate A1-C1 level learner texts, highlighting language characteristics relevant from practitioners’, research and intrinsic CEFR perspectives. The resources and tools created by MERLIN will be made freely available under an open source license. MERLIN for the first time provides immediate, versatile access to CEFR-related learner productions by combining the systematic analysis of indicative learner language properties with innovative computational linguistic analyses for their automatic annotation in support of state of the art information retrieval. MERLIN enables practitioners to empirically relate tests, curricula, and textbooks to the CEFR standards for German, Czech, and Italian. The project thus addresses a broad target audience, with its relevance to anyone teaching, testing, or learning one of the three target languages in Europe. In addition, the project approach and computational architecture is designed to be adaptable to other languages for which CEFR level illustration is needed.