InstantSend was developed by DASH.
InstantX is NOW InstantSend (Rebranded May 2016)
This paper introduces a new concept called InstantSend (transaction locking and masternode consensus). This technology will allow for cryptocurrencies such as Terracoin to compete with nearly instantaneous transaction systems such as credit cards for point-of-sale situations while not relying on a centralized authority. Widespread vendor acceptance of Terracoin and InstantSend could revolutionize cryptocurrency by shortening the delay in confirmation of transactions from as long as an hour (with Bitcoin) to as little as a few seconds.