Police scanner apps are surging in popularity. One developer is donating his proceeds

As thousands of people across the U.S. protest against police brutality, police-scanner apps have surged in popularity. 

One such app, 5-0 Radio Police Scanner, shot up the charts to become the most popular paid app in the Apple App store over the weekend, in both paid and free categories. Some half a million people downloaded the app in the past several days, its developer, Allen Wong, told CBS News. 

Rival apps like Police Scanner Radio & Fire and Citizen also rose to be in the top-10 list on both Google Play and the Apple App store. They have since fallen but remain in the top 30. 

Police scanners, which tap into particular frequencies used by law enforcement and emergency response services, cost several hundred dollars, making them inaccessible to many people. Scanner apps and websites like Broadcastify, use public feeds connected to such apps. Many are free or cost a few dollars.

Wong, who created 5-0 Radio Police Scanner more than 10 years ago, initially started listening to police scanners because he wanted to be a cop as a kid and was curious about their work. He told CBS MoneyWatch that he hoped the app would grow the community of people who listen to police, as well as increase understanding between police and the public.

While both the $5 paid version of the app and the free version of the app have had bursts of popularity before, including during the Boston Marathon bombings of 2013, the current surge in downloads is unprecedented, Wong said. Several million people used the app over the weekend, which saw 500,000 new downloads, he said. Wednesday might turn out to be the busiest day yet, with 145,000 people downloading the app — within striking distance of the peak on Saturday.

On Monday, Wong announced that he would donate proceeds from the app to antiracist groups, including the Equal Justice Initiative.

"It's important that we acknowledge the outrage justifiably provoked by the killing of George Floyd," Wong wrote on Facebook. "We should not continue standing by the sidelines while ignoring those who are facing racial injustice. We must go beyond returning to the status quo and instead build a future where everyone's human rights are protected."

Wong also donated proceeds after the Boston Marathon bombing, he told CBS News.

"I actually don't like when 5-0 Radio becomes unusually popular, because it usually means that some terrible event is happening," Wong said via email. "The way I've dealt with this is to try to help and donate the proceeds to various charities that help the cause."

He added, "It's the least that I could do. Even though my app inherently makes more during tragedies, I don't like making profit from tragedy. I'm already in a comfortable position, and want to lift up others so they can get here, too."

It's not just protesters, or those looking to avoid them, who may want to listen in on police communication. Wong has heard from people who've used his app to avoid tornadoes, or from partners and spouses of emergency personnel who use his apps to keep tabs on their loved ones, he said. 

During times of heightened police activity, the general public could benefit from hearing what's going on with police, if only to avoid a traffic jam, said John Banzhaf, a professor of public-interest law at George Washington University in Washington, D.C..

"If I were in a major city, I would want to know where's the action going on, what is traffic going to be like?" Banzhaf said. "I would detour around the White House, but would I detour around 14th Street and U, or some other route?"

He added, "There is a general public interest in things being open, whether those are things like courts, the legislative functions, or policing."

In recent years, some police departments have moved to encrypt their radio communications, citing the safety of officers as a reason. But just in recent days, public listening to police scanners has revealed some questionable banter. 

Police in New York were overheard talking about plans to "shoot" a crowd and to "run over" a crowd, Gothamist reported Monday. In Chicago, voices on a police scanner reportedly discussed allowing a shooting to play out and not intervene. Both police departments have said they're investigating the transmissions.