The only direct "Vocaloid" free option comes from Yamaha itself.
In the past, Yamaha and partners offered limited-time free voicebanks: vocaloid voicebanks free
However, the term "free Vocaloid voicebank" is tricky. But there are several legal ways to access free or freemium vocal synthesis—including older versions, trial periods, and powerful alternatives. The only direct "Vocaloid" free option comes from
Yamaha offers a 31-day free trial of the VOCALOID6 Editor , which allows you to explore all its features before committing to a purchase. vocaloid voicebanks free