Democrats questioned whether steps taken to flag that President Trump's claims of election fraud were "disputed" had gone far enough.
Republican members of the Judiciary Committee asked whether the tech firms should be taking such action at all.
This was the second time the CEOs had been cross-examined in three weeks.
They were previously questioned by the Senate Commerce Committee last month in what was a more rowdy event.
Once again, the issue of a law known as Section 230 loomed large.