Bitcoin XT is described as 'implementation of a full node that embraces Bitcoin's original vision of simple, reliable, low-cost transactions for everyone in the world' and is an app in the Bitcoin & Cryptocurrency category. There are more than 25 alternatives to Bitcoin XT for a variety of platforms, including Windows, Linux, Mac, Online / Web-based and Android. The best alternative is Bitcoin, which is both free and Open Source. Other great apps like Bitcoin XT are Litecoin (Free, Open Source), NameCoin (Free, Open Source), Dogecoin (Free, Open Source) and Golem (Free, Open Source).
Bitcoin is a peer-to-peer digital currency. Peer-to-peer (P2P) means that there is no central authority to issue new money or keep track of transactions. Instead, these tasks are managed collectively by the nodes of the network.
DASH is an open source peer-to-peer cryptocurrency that uses a system called Darksend to add privacy to transactions. It allows you keep your finances private as you make transactions, similar to cash.
Cardano is a decentralised public blockchain and cryptocurrency project and is fully open source. Cardano is developing a smart contract platform which seeks to deliver more advanced features than any protocol previously developed.