One of those is called "Go Back in Time", and allows users to switch the card used for a transaction even after the purchase was made within 14 days.

The company has been testing the app for the past year and currently has 50,000 sign ups, with 45,000 users on a waiting list. But now it is gearing up to launch the app officially with better features.

Curve is a London, U.K.-based company that has an app which allows you to link all your bank cards to one MasterCard. The idea is to create a hub that can track spending across all your accounts, rather than using several different cards.

That's a problem financial technology or fintech start-up Curve is trying to solve with the launch of its patent-pending "time travel" feature on Monday.

Ever have a situation where you pay on the wrong card and then have to spend time sending money from one bank account to the next?

"The problem that we are trying to solve is that users sometimes use their wrong card or a different card because they don't' have the right card with them or don't have enough money in their main account. It's about trying to resolve friction," Shachar Bialick, CEO of Curve, told CNBC in an interview before the official announcement.

When you pay with something using the Curve card, the money comes from your bank and is paid to Curve. The start-up then pays money to the merchant. But because you've paid Curve, it allows you to switch the account which you paid from even after the transaction.

But Bialick sees a bigger business opportunity from this feature. For example, if Curve partners with a bank, then that lender could identify a person has paid $1,000 for an item on a debit card. But in fact, the bank could then offer credit for this customer's purchase, giving them back the money and allowing the user to pay off a low-interest loan in their own time.

"Most users find it's hard to get a loan, sometimes they want a loan for just a computer. This allows a partner to go in and credit a user for shopping they have already done. The risk is lower because they have already bought it. It's not a payday loan, with the risk very high," Bialick explained.

Curve is trying to take advantage of the explosion of fintech services on the market. There are lots of start-ups that are attempting to eat away at various parts of a bank's business from money transfers to lending. This has led to people using a number of different services but no single interface to interact with them all. Curve's mission is to bring together all of these services.

"The problem that we are facing is that there is a disconnected world of money. As the user you have multiple bank cards and multiple bank accounts. You have around 8 to 12 money tools that you are using on average. But they are all disconnected," Bialick said.

"What Spotify did with music or what Skyscanner did with flights, you will see this convergence happening in the finance space too."