This book constitutes the refereed proceedings of the First International Rapid Mashup Challenge, RMC 2015, held on June 23, 2015, in Rotterdam, The Netherlands, in conjunction with the 15th International Conference on Web Engineering, ICWE 2015. The 2015 edition of the challenge is the first installment of a series of challenges that aim to engage researchers and practitioners in a competition for the best mashup approach. The 6 thoroughly reviewed...