Mobile payment start-up card.io announced a new software development kit (SDK) for its credit card-scanning technology as well as an app that incorporates the technology. Like other mobile POS apps, the card.io app allows users to accept credit cards as payments. The difference is that card.io uses a smartphone's embedded camera to securely scan the credit card number for processing.

With the new SDK app developers can integrate the card scanning technology with their iOS or Android apps to start taking payments. A merchant account is not required by card.io, and funds can be deposited into a bank account or PayPal account, the company said.

Card.io also announced a new app that incorporates the scanning technology. The app, available for both iOS and Android devices, allows anyone with a smartphone to accept a credit card with no hardware required.

The charge for accepting a credit card through card.io is 3.5 percent plus 30 cents per transaction. That's substantially higher than mobile POS rival Square which charges 2.75 percent and no per transaction fee.