The number one app generating cases for police right now is Kik. There's not even a close second.
Kik allows users to message each other anonymously through the app without going through the phone company.
Police say anytime communication is anonymous, there is potential for trouble.
The app is rated for people 17 and up, but millions of younger kids use it and predators do too.
Police say Shea Cutler is one of those predators. He is going to prison for 15 years after pleading guilty to using the Kik app to send and exchange nude pictures with a 14-year-old Tulsa, Oklahoma girl.
He even drove to her house to try to pick her up, but she refused to go.
Police say Cutler was caught by police having sex with another underage girl. That case is still pending. Police say Cutler was communicating with about a half-dozen young girls through Kik.
Police say, like it or not, we are now fighting a war in cyberspace.
"We can't win this war," said Sergeant Malcolm Williams with Tulsa Police Department Cyber Crimes.
Williams says by the time a case gets to them, the damage is done and all they can do is react to it. But he says parents can be proactive because they're on the front lines.
Police say they are getting case after case of "sextortion" that originate from Kik.
"Sextortion" is when someone convinces you to send a racy picture, then they threaten to post that picture online and even send it to your parents unless you do one of three things: send them an even sexier picture, have sex with them or give them money.
Police say kids want to avoid embarrassment so they give in to the extortion and things snowball out of control.
"They're threatening if I don't do this, they'll put it on my Facebook page or put it where everybody can see it and that fear of embarrassment tends to make people do things they normally wouldn't do," Sgt. Williams said. "If you have a lack of judgment and make a mistake, go talk to mom or someone, let's not compound the problem."
Here are the reasons police say Kik is bad for kids: the app's settings do not block approaches by strangers. Porn bots send unsolicited porn regardless of the privacy settings.
The hidden apps are designed for adults and can include pornography, and most of them are "chat with strangers" apps.
Parents cannot share a Kik messenger account with their child to supervise them, and if you log into your child's account from another device, it deletes all their messages and conversations.
Kik has chat groups with lots of members your child can join and the only way to log out of Kik is to do a total reset of the device.
"Take the initiative to talk to your kids, take the initiative to randomly go through your kids' phones, take the initiative to know who your kids are communicating with," Sgt. Williams said.
Police say no app is bad by itself, it's how some people misuse it.
Kik's website says it cooperates with law enforcement and it sponsors the annual Crimes Against Children National Conference.
Kik says when it comes to approaches by strangers, all messages from strangers go into a "new chats" channel and are automatically blurred. A user has to actively agree to chat before a conversation is initiated.
When it comes to porn bots, all unsolicited messages are also blurred and separated into the "new chats" channel. Users can report spam directly from the chat and user profile pages.
And when it comes to hidden apps, Kik says there are many hundreds of web apps on Kik, the vast majority of which are not about chatting with strangers.
Teach kids not to accept friend requests or messages from people they don't know, and they should never send any kind of intimate photo online.
Kik's head of privacy Heather Galt released the following statement:
"User safety is extremely important to Kik. We've built unique safety features right into the app, allowing people to block, filter, or report inappropriate behavior. We are also actively involved in a broader societal effort to educate parents, kids, and law enforcement about online trust and safety. Unfortunately, child exploitation is an industry-wide issue that affects any provider of online communication tools, including Facebook, Twitter, Reddit, and Snapchat. Kik has partnered with global anti-child abuse organization Virtual Global Task force (VGT) and implemented Microsoft PhotoDNA Cloud Services, industry-leading technology that helps identify and eliminate abusive content (See details). We take a proactive approach to trust and safety, and continue to develop and implement technologies and partnerships to keep Kik safe."