Behind the scenes: Making of Flipkart’s ‘Saved Card’ feature


Behind the scenes: Making of Flipkart’s ‘Saved Card’ feature

[Editorial note: recently launched Saved Cards feature. Senior Product Manager, Abhishek Rajan shares the tech behind implementation]
A click on time saves nine. It may actually save more than nine (around twenty seconds on an average), if you use the new saved card option on This post will describe some of the product/UX challenges we faced while implementing this, and the thought process behind some of our  decisions.

One of the early mock-ups of the checkout interface

To click or not to click

The adoption of the saved card feature depended to a large extent on just one single checkbox option – “Save this card for future payments”. So it was only natural for us to give it its fair share of time and ensure that we got it right.

There were primarily two user concerns that we wanted to address when presenting this option:

  1. What’s in it for me?
  2. Why should I trust with my card details?

The guiding principle was to keep the communication short & crisp, which made it challenging to comprehensively address both the concerns in one shot.

We decided to address the first concern by explaining the user benefit through the display text of the checkbox.  We addressed the second concern by using a “Learn more” mouse over tooltip. While both the concerns are important for an e-commerce user, has earned a certain level of trust among its customers and hence the first concern deserved more prominence.

The next logical step was to finalize the exact text to be displayed for this checkbox. We are currently running various A/B experiments on the text to arrive at the most optimum combination.

The Mask

When displaying a card number on a website, masking is typically done to ensure that the card number is not fully visible to the users. For the saved cards, we initially planned to display the first 6 and last 4 digits of the card number, keeping the remaining digits masked. We came up with different masking options:

5566 20** **** 1234
5566 20## #### 1234
5566 20XX XXXX 1234
5566 20xx xxxx 1234

We settled for the last option because it looked neater and effectively played down (literally) the masked digits. When we released the saved card feature to an internal audience, one common feedback was that we were leaving too many digits unmasked, especially for Amex cards where we were revealing 10 out of the 15 digits.

One could argue that with 6 masked digits for a typical 16 digit VISA/Master card number, the chances of correctly guessing the card number are 1 in a million, but most users typically aren’t statisticians of sorts to appreciate the laws of probability. The user feedback was thus incorporated and the version that finally went live displays only the first 2 and last 4 digits of the card number.

Cards have a shelf life too

Almost all cards have an expiry date (barring a few Maestro cards). Imagine if your user finds out at the time of checkout on your website that his card has expired, and cannot be used to make the payment.  This can be very frustrating, and defeats our goal of reducing friction.

So what do you do if your customer’s credit card is nearing expiry?

If we were the card issuing bank, we would courier a new card to the customer. Since we can’t do that, the next best thing that we can do for the customer is to remind him that it’s time he got a new card.

If a card is nearing its expiry date then the message “Card is expiring” gets flashed near the card number. Try adding a card through “My Account > My Saved Cards” on and specify the expiry date as current month to see this in action.

The next question that came to mind was – what to do with the saved card once it expires?

Initially we thought we’ll keep displaying the expired card till the user gets sick of it and finally removes it on his own. But why create more noise for our wonderful users? So we decided to display the expired card only for a month, after which the card will be removed automatically. And all this while the card will not be selectable and the card logo will be displayed in gray scale to make it appear unusable.

One of the suggestions received from our internal users was that we should send an email alert to our customers as and when their credit card expires. While the intention looked noble, we felt it would be too intrusive and most online users may not particularly appreciate the intent.

Expired Card Mockup
Expired Card

My Corporate Card

We realized that power users would like to save and use multiple cards while shopping online. However, it may not be intuitive enough for them to distinguish between their cards by just looking at the first 2 and last 4 digits. If the user is required to take out the card from his wallet to match the last 4 digits and accordingly select one of the saved cards for payment, then we would feel that we haven’t done our job well. So we added the card label, which could be used to give a unique personalized name to every saved card. E.g. My Corporate Card, My Shopping Card, etc.

However, this option is available only in My Account section. We deliberately removed this option from the Checkout flow to keep the number of input fields on the card payment page to the minimum.

Remove this card

Typically, sites that offer the saved card feature do not provide the option to delete the saved card during the checkout process. However, from day one, we were clear that we wanted to offer the option to enable users to delete their saved cards even on the checkout page.

From my previous experiences, I had learnt that many users select the card save option (like the mandatory T&C checkbox) without realizing that it will cause their card to be saved on that website. When such users return for a repeat purchase, they get surprised to see their card appearing as saved and frantically look for an option to delete it. If they don’t find the delete option, they will end up contacting customer support. End result, bad customer experience and additional operations overhead. Hence the explicit “Remove this card” self-care option on checkout.

There’s another interesting fact about the “Remove this card” option. Most users who click on it would expect to receive a dialog box for a final deletion confirmation. We felt this was a redundant step/click that should be avoided.


If the user has a saved credit card, his saved card (irrespective of the card’s bank) appears on selecting the Credit Card payment option on the checkout page. This behavior had to be modified for the Credit Card EMI payment option. Reason being, the EMI option for a given bank applies to only the credit cards issued by that same bank.

In other words, we shouldn’t display a saved ICICI Bank credit card if the user selects HDFC Bank EMI option. We had to therefore ensure that a saved ICICI Bank credit card is displayed only if the user selects ICICI Bank’s EMI option and is not displayed for any other Bank’s EMI option. This required us to identify the issuing bank name of the credit card, without explicitly asking the user for this information. This was challenging, though not impossible. Wondering how we solved this? Read on.

Card BIN Laden

Did you ever notice that all VISA credit/debit card numbers necessarily begin with a “4” while MasterCard begin with “5”?

The first 6 digits of a credit/debit card number are referred to as the BIN or the Bank Identification Number. This is a magical number that can reveal almost everything about the card – whether it’s a VISA or MasterCard, Credit or Debit card, Platinum or Gold card, Indian or US and also the Bank that has issued this card.

Unfortunately, we didn’t come across any single authentic source of BINs that was both comprehensive and accurate. There are several paid BIN databases available online, but none had the acceptable level of accuracy that we were aiming for. So we decided to compile our own list of BINs by collating information from multiple sources including the issuing banks and online BIN dbs.

One of our sharp dev team members came up with this really cool idea (please don’t try this at home!). We generated dummy card numbers for the BINs for which we didn’t have any details. Next we attempted a card transaction using these dummy numbers. The payment gateway redirected us to the 3dsecure page. Voila, the 3dsecure page contains the bank name of the card!

Another interesting trick to confirm whether a card is credit or debit, takes advantage of RBI’s recent mandate on reduced processing fee on debit card transactions. As a merchant, we receive a daily settlement report from the processing banks for each card transaction on our site. The report contains the processing fee for each transaction. Transactions with the lower fee would be debit card transactions.

Default card label

The BIN list compilation effort helped us introduce another favourite feature of ours – the default card label.

As mentioned earlier, when the user is saving a card during checkout, there is no input field for specifying the card label. We expected 80-90% of our users to save their cards during checkout process. For the benefit of such users we wanted to specify a default card label.

We looked at two options for the card label:

  1. Card holder’s name
  2. Bank name

We realized that most of the time, users will save their own cards. In such a case, using the card holders name as the card label wouldn’t help in differentiating between different card.

On the other hand, users are likely to have cards from different banks.  We decided to use the bank name suffixed with the card type (Credit/Debit) as the default label.  This provides a reasonable default for most users.  And for duplicates, users can change the label later.

Guess what!

When displaying the saved cards on the checkout page, if a user had saved multiple cards, we had two options:

  1. Display all the cards unselected and let the user choose the card
  2. Make a smart guess for the card that the user is most likely to use and show this card as pre-selected

The 2nd option had the advantage of one less click (~ more convenience for user). And even if our guess failed, worst case scenario, the user will have to click on some other saved card. That’s no worse than option 1. So we intuitively went for the 2nd option.

Now we had to figure out an algorithm to predict the card that the user was most likely to use. We decided to build a frequency counter that would track the number of times each saved card had been used to make a payment. The most frequently used card should be the best guess.

It seemed logical till we were confronted with a use case wherein a user switches from an old frequently used card to a brand new card. An extremely probable scenario for any user. Imagine if the user’s old saved card had a frequency count of 15. He will now have to use his new card at least 16 times before it gets picked by our so called “smart” guess algorithm. We thought why not refine our frequency logic and take into account only the last ‘x’ transactions instead of all transactions, to determine the most frequently used card. Now again, depending upon the value of ‘x’, the guess may work for some and may not work for others.

Sometimes, we unnecessarily complicate a problem that may have a rather simple answer. In this case the answer seemed to be x=1. Why not just look at the last used card? That would work for most of the use cases, except if the user keeps shuffling between his saved cards, a use case that we decided to keep outside the MVP (minimum viable product).

[Reproduced from Abhishek’s post]

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