SSL encrypts the transmission of the website being displayed so it is mainly used when entering personal information, credit card information and passwords.
Pixiv uses encrypted transmission using SSL when logging in with password, registering for pixiv Premium and changing e-mail address or password.
As of March 21, 2017, encrypted transmission using SSL is used for all pages on pixiv smartphone versions.
SSL has been implemented for the pixiv computer version as of April 18, 2017.