CeVIO AI is a [vocal-synthesis] tool made by CeVIO that supports singing synthesis as well as [tts]. It is quite new with a release date of Jan 29, 2021. It uses a [[rnn]]-based architecture which is also used by [synthesizer-v] and other modern vocal synthesis tools. It was developed in cooperation with the Nagoya Institute of Technology which has worked on other vocal synthesis tools in the past such as [sinsy].
Along with most other singing synthesis tools out there, there are several different voice banks that can be switched between.
Here's a really nice song that stood out to me when I heard it because I wasn't familiar with CeVIO AI at the time: https://www.youtube.com/watch?v=XqKbuEDvaf8&list=RDyzF1LVly7Jw It features the KAFU voicebank.
Cevio fandom overview page: https://cevio.fandom.com/wiki/CeVIO_AI