Herein, we report the preparation and use of m-carboxybenzenesulfonyl azide as a diazo transfer reagent. This compound is an inexpensive and potentially scalable alternative to many of the diazo transfer reagents currently available, most of which have hazards associated with their use. Its usefulness and suitability as a diazo transfer reagent was assessed on the basis of cost, safety and its effectiveness in diazo transfer to a variety of different substrates. (C) 2018 Published by Elsevier Ltd.