OpenToonz is based on the software "Toonz", which was developed by Digital Video S.p.A. in Italy, customized by Studio Ghibli, and has been used for creating its works for many years. Dwango launches this OpenToonz project, in cooperation with Digital Video and Studio Ghibli.

https://opentoonz.github.io/e/

Since the software "Toonz", which is the original version of OpenToonz, was first used for some cuts of Princess Mononoke, it has been used in the ink and paint, color design and digital composition process of almost all of works of Studio Ghibli. After "Arrietty/The Secret World of Arrietty", it was customized inside the company, and evolved to become more usable according to its production style.