The Bitcoin protocol allows to save arbitrary data on the blockchain through
a special instruction of the scripting language, called OP_RETURN. A growing
number of protocols exploit this feature to extend the range of applications of
the Bitcoin blockchain beyond transfer of currency...
A point of debate in the
Bitcoin community is whether loading data through OP_RETURN can negatively
affect the performance of the Bitcoin network with respect to its primary goal. This paper is an empirical study of the usage of OP_RETURN over the years. We
identify several protocols based on OP_RETURN, which we classify by their
application domain. We measure the evolution in time of the usage of each
protocol, the distribution of OP_RETURN transactions by application domain, and
their space consumption.