Age ratings aren't enough

In response to porn flooding its video-sharing app, Vine, Twitter recently upped the age for participants from 13 to 17 years. But slapping an age warning on an app does little to protect kids from unsuitable material and overtures from strangers.

All it takes is an unsupervised click to pass through the warning page and download a mature app. And just because an app has a lower age rating doesn't mean it's safe for kids. Parents need to do their homework. Read more: Shielding Kids from 'NSFW' Apps

Be aware of the more popular apps that could land your kids (and you) in uncomfortable and sometimes dangerous situations. Apps that share your child's location, allow them to chat with strangers, offer easy access to mature material and encourage cruel behavior are risky. Here are eight to watch out for.

Snapchat

This photo- and video-messaging app lets kids take pictures and send them to friends and groups of friends. A few seconds after they arrive, the photos automatically disappear. While Snapchat can be a lot of fun, it can also tempt kids to snap and send photos that they wouldn't risk if not for Snapchat's disappearing act. And a dexterous kid can still take a screenshot, even though the app tries to prevent it by requiring a finger on the screen to view a Snap.

Facebook Poke

Poke is Facebook's version of Snapchat. But Poke is a little riskier because it makes it so easy to send to any number of Facebook friends. Messages can be set to disappear in as little as a second. Like with Snapchat, senders receive alerts if screenshots are taken by receivers, but by then it's really too late to prevent the photo, video or text from being shared with others.

KiK Messenger

Ranked seventh in the App Store's social networking category, KiK is a messaging service for all smartphones that lets users talk to others, send pictures, files and ecards. But KiK's privacy feature — using a made-up KiK username instead of a phone number — has helped it become a place for strangers to connect. Many of the more than 90,000 reviews in the App Store read like personals ads. For instance, "Looking to chat with some sexy females … ill talk and trade pics of anything ;)"

Lulu

Brand-new to the U.S., the girls-only app is designed for rating guys they know. Reviews are posted anonymously, and users are encouraged to be positive. Nevertheless, Lulu wades into some iffy territory by allowing girls to tag a guy as a weed smoker, rate his sexual prowess and allude to medical conditions. Definitely mature content, and even though it's "all in fun," guys' photos from Facebook are displayed along with their assigned ratings, which happens without their permission. (Access and visibility is based on Facebook settings.)

Tumblr

The popular blogging app recently changed its rating in the App Store to 17+ and removed sexually explicit tags, such as #porn and #sex. But it's still a place to promote harmful behaviors, such as the "pro-Ana" girls who practice anorexia and bulimia. Tumblr began last year to remove users who encouraged self-harm, but a tag search turns up plenty of troubling posts, such as "Note to self in case tempted, from Ana: He's so out of your league, and he's not going to go for someone who's fat and ugly."

9GAG

There is no shortage of photo humor apps, but 9GAG has content that parents may find more disturbing than funny. For instance, in the first 10 promoted posts, we saw plenty of profanity, a cartoon about rolling blunts and a bedroom photo featuring a young girl with two others dressed as unicorns — all in the optional "Safe Mode" that can be turned on in a user's settings. This app is rated 12+.

iMeetzu

iMeetzu is a chatting app that connects users with strangers. The homepage headline even reads: Meet a stranger. Worse, kids can meet people across the world or opt to find people nearby. It has a rating of 17+ for just about every type of objectionable content, including frequent/intense sexual content or nudity, frequent/intense drug use references and mild realistic violence. A user warns in a review in the App Store, "Don't get it. Preverted [sic] guys are on here."

Poof

Poof is an app that hides other apps from nosy viewers, which could include Mom and Dad. Made by Cydia, it can be downloaded only to "jailbroken" iPhones. Cydia earlier this week released a "permanent" jailbreak program for the iPhone 5 and new iPads called Evasi0n. While there may be good reasons to jailbreak a phone (and it is legal), it's probably not wise to allow your kids to do it. Furthermore, the only instances of iOS malware found in the wild have been on jailbroken devices.

8 Apps Your Kids Shouldn't Download