Ahead of the 2018 US midterm elections, concerns about social media’s role in the election process have been front and center.
Dorsey will appear Wednesday before the House Committee on Energy and Commerce while Sandberg will appear before the Senate Intelligence Committee.
Republicans have accused the social media giants of political bias, alleging that search results have been skewed to bury conservative views.
Twitter has denied the allegations, saying that it has not banned any accounts for political reasons.
"We believe strongly in being impartial, and we strive to enforce our rules impartially. In fact, from a simple business perspective and to serve the public conversation, Twitter is incentivized to keep all voices on the platform,” said Dorsey in his written testimony.
Dorsey argued in his written testimony that Twitter plays an important role in democracy by connecting elected officials with constituents and offering news organizations the opportunity to live-stream events to the public.
“The notion that we would silence any political perspective is antithetical to our commitment to free expression,” wrote Dorsey.
Dorsey plans to discuss Twitter’s algorithm and shed light on how users’ timelines are affected by filtering, conversations, safe search and behavioral signals and safeguards.
The testimony will address specifically Russian interference in the 2016 presidential election and the steps the platform has taken to combat hostile foreign influence.
Dorsey said the company identified 50,258 automated accounts, also known as bots, that were linked to Russia and tweeting election-related content. That amounts to 0.016% of total Twitter accounts.
These accounts tweeted a total of 2.12 million times, accounting for approximately 1% of election-related tweets.
The company found that two of the most-active accounts were linked to Russia Today, a network funded by the Russian government, and plans to donate the US$1.9mln that RT spent on advertising to academic research into elections and civil engagement.
Shares of Twitter fell nearly 1% to US$34.85 in Tuesday afternoon trading while shares of Facebook sank more than 2.5% to US$171.30.