The man on trial is alleged to have abused dozens of children aged from five to 14 who were living across the country, from Skåne in southern Sweden to Norrbotten in the north.
He is accused of finding his victims online and remotely carrying out a range of offences, including exploiting them by asking them to pose suggestively and asking some of the children to sexually abuse one another.
It is not standard practice for Swedish media to report the identity of criminal suspects, but the TT news agency described the suspect as a 22-year-old “from the Stockholm area”.
His trial is being held in Sollentuna, north of Stockholm. The hearings will take place behind closed doors, however the prosecution has said it is planning to use the man's Instagram account as part of its evidence against him.
Seventeen children are also set to give evidence via video link from 14 different district courts. Many of the other victims have been deemed too young to participate, with police interviews set to be used instead.
A total of 96 children are involved in the case.