The company’s card aggregates all your cards and allows you to switch cards after a transaction has been completed.

In what is a world first, a London-based startup has teamed up with Mastercard Inc to launch a payment card that allows users to retrospectively choose a different credit or debit card for a purchase they have already made, in what has been described as “financial time travel”.

Starting from Tuesday, London-based startup Curve, is set to offer customers the chance to “go back in time” and change the card they had used for their transaction. This is applicable for up to two weeks after the purchase.

Although on Monday, Curve said it would provide the names of two large international banks whose backing they have, they have however yet to provide any further details.

Curve has applied for a patent for this new tool which aggregates all customer cards under their card. Consumers can carry multiple cards and switch between cards when they make a purchase through a smartphone app.

Founded in 2012, London-based Curve is among a group of startups which aims to ease the difficulties surrounding digital technologies and make banking more user-friendly.

As per Shachar Bialick, Curve’s Chief Executive, the “time travel” feature allows consumers the convenience of choosing a form of payments for any given transaction.

Case in point: while a user might have funds parked in their current account days after a purchase has been paid for with a credit card, they could switch the transaction to a debit card to avoid paying interest fees.

“The user can manage their cash flow much better. It’s very hard to make the decision at the point of sale,” said Bialick

He went on to add, this functionality has the potential to enable users to take advantage of card rewards.

When a user switches cards, the change occurs only on Curve’s platform, so merchants see only the final transaction and users are not charged for card processing fees twice.

Incidentally, rewards gained through the first purchase will be reversed if that card is changed, clarified Curve.

The company disclosed that its program is still in “beta” testing mode, and has registered 50,000 sign-ups.

Their card has so far been used for over $64.7 million (50 million pounds) in transactions so far.

Curve’s program will come out of beta later this year.

(1 pound = $1.29)