The man, in his 40s from Uppland county, allegedly told his victims - young girls from Scotland, the US and Canada - he would murder their families if they did not comply.
Swedish prosecutors have charged him with rape despite the lack of physical interaction, due to the way the suspect used blackmail.
So far, 18 of the 27 victims have been identified with the help of Scottish, US and Canadian authorities.
The Swedish police have labelled the suspect's modus operandi 'sextortion' - sexual blackmail.
The children have reportedly been threatened with a number of different types of reprisals in case they did not perform the sex acts the man demanded.
The man would find his victims on social media and groom them with flattery before moving on to blackmail.
One of his victims, an American girl the man contacted via social media in December 2015, was 14 years old at the time of the assaults.
In an interview with an FBI expert, she revealed how initially threatened to publish images of her on porn sites if she did not do his bidding during a Skype video chat.
She told police he forced her to 'undress, touch her genitals and penetrate herself with fingers and objects, sometimes causing herself pain' while the threats escalated.
He threatened to 'shoot her and her family'.
'He said he know what school I go to and where I live,' she said in the interview accessed by SVT.
'I flipped out, I cried and wrote to him that I'd do anything,'
The man then forces her to carry out sex acts involving a dog.
'This is one of the worst things I've ever seen,' one of the investigators, Jörgen Lindeberg told SVT.
The man is today appearing in Uppsala District Court, some 44 miles north of Stockholm, charged with aggravated child rape, aggravated sexual assault, abuse of child for sexual posing and child pornography.
Authorities believe it is the first time a person has been charged with child rape without any actual physical contact on this scale.
If prosecutors are successful, he will be the first person in Sweden convicted of 'digital rape'.
The case continues.