Since their emergence, crypto-currencies have attracted a lot of attention, both in the public sphere and in the academic world. One of the particularities of this alternative currency is that it is a complex socio-technical system, which cannot be studied or understood from the perspective of a single discipline. Monetary innovation, societal and environmental perspectives, decentralized computing systems, financial issues, legal questions: all these issues are intertwined and require researchers to think outside the box in order to understand the challenges and opportunities offered by crypto-currencies and other digital alternative currencies. The objective of these days is to bring together all young researchers -doctoral students, post-doctoral students- interested and working on the subject in France or in the French-speaking world, to discuss their respective work in a friendly atmosphere and a spirit of openness, conducive to the discovery of new areas of research and the launch of collaborations.