The app garnered about 1.3 million global downloads on the App Store Monday, according to app data and analytics website Apptopia.
"We estimate Signal has been installed 63.1 million times in its lifetime. Signal has been breaking its own daily download records since Saturday," Apptopia Insights vice president Adam Blacker told FOX Business.
Signal is an encrypted messaging app, meaning that the company cannot access any messages or calls made by users on the app.
"These types of shifts in messaging and social networking apps are not unusual," Amir Ghodrati, director of market insights at app analytics company App Annie, said in a statement. "Due to the nature of social apps and how the primary functionality involves communicating with others, their growth can often move quite quickly, based on current events."
He added that "users consistently spend more time in messaging apps than in social media apps; 67% more time on average as of H1 2020. Messaging apps that provide privacy features saw the greatest engagement growth in H1 2020. These apps saw on average 30% more active users than the alternatives."
On Jan. 4, Signal ranked No. 750 in overall U.S. downloads, according to App Annie. The number continued to jump until the app reached No. 1 in overall U.S. downloads on Sunday.
The app has benefited in popularity after people like Edward Snowden tweeted about it in 2015, with Tesla and SpaceX CEO Elon Musk recently telling his followers to use the service, while simultaneously taking a shot at Facebook.
Encrypted messaging app Telegram also surged to the No. 2 position among free apps on both Google Play and the App Store Tuesday.
The two apps have come into the limelight recently after some people using the Facebook-owned encrypted messaging app WhatsApp expressed concern with a privacy update set to roll out in February and first announced in October.
The update stated that businesses communicating with WhatsApp users through the app, via phone or by email "can see" what users are "saying and may use that information for its own marketing purposes, which may include advertising on Facebook" if users opt to sharing that information.
WhatsApp later clarified the update in a January message, saying Facebook will not have access to any of its users' private messages or calls.
"We want to be clear that the policy update does not affect the privacy of your messages with friends or family in any way. Instead, this update includes changes related to messaging a business on WhatsApp, which is optional, and provides further transparency about how we collect and use data," the app said in a blog post.
WhatsApp ranked No. 27 and No. 21 in overall U.S. downloads on Jan. 3 and Jan. 7, respectively, until it hit No. 38 on Sunday.
WhatsApp said Facebook will not have access to its users' private messages or calls, shared locations, contacts or groups. Users can also set their messages to disappear if they so choose.
Big Tech companies have made a number of policy changes and updates since Wednesday's Capitol riots in an effort to quell violent or conspiratorial rhetoric on their platforms, causing uncensored social apps like Parler, Gab, Signal and Telegram to see surges in downloads.
Fox News' Chris Ciaccia contributed to this report.