Well, if you need more proof that you don't always need a blockchain, Webcash ( https://webcash.org https://webcash.org ) might be it because Webcash just uses

Well, if you need more proof that you don't always need a blockchain, Webcash ( https://webcash.org https://webcash.org ) might be it because Webcash just uses a central database for double spending detection. A few of the early users were commenting that the project has put lots of altcoins to shame from an architectural standpoint.