The social media websites have faced tough questions from MPs concerning the growing level of hateful content found online, including neo-Nazi content and videos of tragic events, including the recent New Zealand mosque shootings which were filmed by the shooter and uploaded to Facebook.
According to the BBC, MPs accused the platforms of "failing" to deal with the issue, despite repeated assurances that their systems were improving.
Yvette Cooper said: "It seems to me that time and again you are simply not keeping up with the scale of the problem."
Facebook's head of public policy, Neil Potts, said the reason the tragic New Zealand shootings remained on the site was due to users editing the clip in a way that let it skip over Facebook's automated system, which is supposed to take down videos that cause harm.
He said: "This video was a new type that our machine learning system hadn't seen before. It was a first person shooter with a GoPro on his head. If it was a third person video, we would have seen that before.
"This is unfortunately an adversarial space. Those sharing the video were deliberately splicing and cutting it and using filters to subvert automation. There is still progress to be made with machine learning."
Executives from the three companies were asked if they actively shared information about those posting terrorist propaganda with police, but all three claimed they only did so when there was "an imminent threat to life".
Neil Potts added that "open internet" is still the way forward, but understands why some governments - including Sri Lanka, who recently suffered tragedy with several bombings - want to block its citizens from getting on social media.
He said: "We feel it is better to have an open internet because it is better to know if someone is safe. But we share the concerns of the Sri Lankan government and we respect and understand that."