Longhorn by BullPay allows developers to add blockchain support to their applications. The API delivers enterprise class features including real-time and historical transactions, summaries, and auditing data. Longhorn is a REST interface with JSON responses and API Keys are used for authentication. The API uses a patent-pending memory-mapped database technology which provides 5 blockchains (Bitcoin, Litecoin, Ethereum, Dash, and Dogecoin). Litecoin TestNet is also supported. The API currently offers 12 endpoints for sending transactions, retrieving summaries, and more. A free package is available that allows for 5,000 calls a day.