You probably lock your front door when you're not at home, your car when you're not driving, and your smartphone when you're not using it.  But, have you ever thought about locking your credit or debit card when you're not making a purchase?  New apps are designed to do just that: prevent unwanted charges by letting users "turn off" their cards at the touch of a smartphone.

"That was really the feature that stood out to me most, where I could say it's time for me to turn this off and just know that I have the peace of mind that no one can get to this account but me," said Scott Kilmer, who got a flyer in the mail from his bank, First Financial Bank, letting him know about a new app to lock his debit card.

Here's how Kilmer's app works:  Open the app and toggle the button to "activation" and the debit card is "on" and transactions are approved.  But toggle the activation switch the other way, and try to buy something, the card is declined.  

"We're all familiar with the bank systems that identify suspicious activity, but this is one that actually stops the fraud before the transaction occurs," explained Nessa Feddis with the American Bankers Association.

Robb Gaynor of Malauzai Software, the maker of the app Kilmer uses, predicts this technology will be the next big thing in banking, and says right now more than 80 smaller banks and credit unions are offering their app for debit cards. He adds the functions of this technology go beyond turning a card on or off.

"You can also do things such as: asking for ATM limit increases, point of sale increases, or letting the bank know if you're going to be outside of the country," Gaynor explained.

Keep in mind though, in order to change any card settings with an app, you've got to be digitally connected.  If you lose your phone or the battery dies when your card is locked, you could be looking for a "Plan B" to get money or make a purchase. 

Feddis, with the American Bankers Association says these applications could be beneficial to customers and to banks.  But when it comes to security, nothing is foolproof.

"Any system can be compromised it's a matter of staying one step ahead of the fraudsters and as they become- if this system becomes more popular fraudsters of course will then try to break down the barriers," warned Feddis.

But Gaynor says his company is ready for that.

"Mobile banking is secured in multiple layers. From things such as embedding certificates in the device and on the phone, and verifying those certificates as a consumer logs in, to checking if a device has been jail broken, if malware's been installed on the Android phone," explained Gaynor.

Kilmer says he trusts the app he uses and hopes it will help keep crooks "locked out" of his account.

"I know exactly where my money is being spent and better- where's is not being spent," he said.

The American Bankers Association recommends you still keep a good eye on your account even if your card is "locked" most of the time.   And, though fraudulent transactions can be a pain to dispute, they point out customers are not on the hook for them financially.  They say whether or not more big banks will adopt this technology depends on whether it grows in popularity at the banks that already use it.

Links to banking apps: