The days -- and possibly weeks -- after Election Day will be a huge test for platforms like Facebook, Twitter, and Google's YouTube. Doctored videos that could potentially be spread by anyone; fake accounts that could pop up anywhere; and tweets from President Trump himself could all contribute to undermining the result of the election and perhaps even stoke offline violence.

CNN Business spoke to more than a dozen people who are either employees at the major social media platforms working on the teams countering misinformation and extremism or people who work directly with those teams at the companies.

CNN Business granted them anonymity so they could speak about their work more freely.

"My biggest fear at this point is something totally unexpected happening that no one predicted," one Big Tech employee said. "This year we've all been preparing and working through scenarios for every possibility that we can think of, but this year has taught me not everything can be predicted."

Hyping the idea of the threat of the "other side" is something Big Tech employees are expecting around Election Day.

Multiple people who work for the tech platforms said they see a potential for domestic groups to stoke tensions and violence on the ground and then for foreign groups to possibly exploit that and fan the flames.

But the top concern for two of the Big Tech staffers who spoke with CNN Business wasn't foreign actors, nor some faceless anonymous account. It was Trump. One said, "the biggest threat to [the] democratic process -- and to societal stability as a whole -- is the President and his party."

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Here's what Big Tech employees are worried about on Election Day - CNN