Well, Blockchain dot io exchange is a decentralized exchange that supports different kinds of cryptocurrencies, in this case, the exchange supports a limited number of cryptocurrencies, not even up to 10 in total. This Exchange was founded in France, in my years of research, this was one of the first exchanges that i discovered in France.
Presently, registration is not possible as the exchange claims ti be undergoing an update and this will lead to it migrating from Blockchain dot io to Paymium™. The exchange doesn't really look active, I checked the telegram group of the exchange but there hadn't been any form of discussions since February 2021.