Neural network based singing voice synthesis library
Open-source: NNSVS is fully open-source. You can create your own voicebanks with your dataset.
Multiple languages: NNSVS has been used for creating singing voice synthesis (SVS) systems for multiple languages by VocalSynth comminities (8+ as far as I know).
Research friendly: NNSVS comes with reproducible Kaldi/ESPnet-style recipes. You can use NNSVS to create baseline systems for your research.
Note that NNSVS was originally designed for research purposes. Please check out more user-friendly ENUNU for creative purposes. You can find a practical guide for NNSVS/ENUNU at https://nnsvs.carrd.co/ (by xuu). A detailed tutorial for for making voice banks can be found at NNSVS Database Making Tutorial (by PixProcuer).