The card reader

Analysing the entry-level card readers, and the user experience of connecting these devices to their apps.

Photograph by Built for Mars

Hardware is notoriously difficult to get right. Once a device has been shipped, there are limitations to what can be changed.

So this chapter explores the physical card reader, and what the experience of setting up this device is really like.

It also compares these readers to new mobile point-of-sale (mPOS) initiatives, such as the Visa ‘tap to phone’ technology.


The incumbent provider Verifone performed considerably worse than iZettle, Square and SumUp.

Key takeaways


Why your power-on times matter.


What we can learn from video games.


Why you should be generous with accessories.


How removing a click may create a moment of magic.


The problem with instruction manuals.

Case studies

This chapter only has 3 case studies, because Verifone’s device arrived already set-up.

Benchmarking the experience

Firstly, how easy was it to connect and activate my card reader? Well, for iZettle, Square and SumUp, this was all done via the app.

Number of clicks to connect card reader






Verifone took a different approach. Because there’s no accompanying app, they set up your device for you, before sending it out.

This would have been fine, if it worked.

Verifone sent my device out misconfigured. It was associated to a business called ‘Grapes Cafe’, and because of this, it was totally unusable.

I assume that this was a rare event, because it took 3 business days and more than 2 hours on the phone with technical support to work out what had happened.

And this highlights why hardware is so problematic; they couldn’t debug it remotely—I had to run all the diagnostics myself.

This was exacerbated by the fact that the technical support staff had to jump around between ~10 different internal portals.  

Ultimately, I was left for 5 calendar days without a working device.

The experience

But, at last I had 4 working devices, and could compare the broader experience of connecting and using this hardware.

1. Power on time

Imagine this; you’ve just opened up your cafe for the day, and have served your first customer. But while reaching for your card reader, you realise that you forgot to turn it on as part of your morning routine.

You both have to wait while the device powers up. How long would this process need to be before small talk dwindled and the embarrassment set in?

So, I tested how long it took for the devices to be ready and usable, after being off for more than 12 hours.

Number of clicks to connect card reader





Seconds to power on

iZettle’s and SumUp’s devices power on more than 5x quicker than Square’s, and 15x quicker than Verifone’s.

Verifone consistently took more than a minute to turn on. Try and fill a minute with small talk, it’s really difficult. And even Square’s 22 seconds feels like an uncomfortably long amount of time.

And these devices turn themselves off after a certain period of inactivity. So this isn’t just a once-a-day issue, but could happen many times.

Number of clicks to connect card reader




Seconds to power on

Note: Square’s time of 2 hours is what they say. I can’t test this because it has no screen, and so no way of seeing when it’s off—without waking it back up. And Verifone let you change the auto-off settings, but the default value—which most people will stick with forever—is for it to never power off.

This demonstrates two approaches to battery life preservation:

1.  Quick start. iZettle and SumUp are so fast to turn on, that they can afford to go to sleep very frequently. 

2.  Sleep less. Square and Verifone take much longer to turn on, so they sleep less frequently.

The point here is that if you infrequently make sales—like an antique furniture store—you might find yourself waiting 22 seconds for every single payment.

🔋 Power-on times

Your UX includes the time it takes for your hardware to power on, so do whatever you can to reduce this waiting time.

2. Auto power-on

Often you can look at the gaming industry for cues on how to build better products. For example; one technique used to keep the player entertained while a new area is loading, is to put them in a lift.

The player walks into the lift, presses a button and waits. Unaware that outside those four walls, the game is frantically loading elements for the next scene.

When the game has loaded completely, the lift doors open, and the player is in a new world. As far as they’re concerned, this was a realistic simulation of a lift, not a means of hiding a loading process.

You’ll see why this is relevant if we delve into the coffee shop example a little deeper. This below would be a typical coffee shop process:


Serving the customer

i.e., taking order, brewing coffee and handing over drink.


Typing an amount into your keypad

i.e., inside the application.


Grab / point to the card reader

i.e., ask the customer to tap their card


Taps card

i.e., transaction complete.

It’s mundane and works well. But if—like in my scenario—you only realise that the reader is turned off when you go to make a sale, then there’s an extra step:


Grab / point to the card reader

i.e., ask the customer to tap their card


Turn card reader on and wait

i.e., small talk while it turns on.


Taps card

i.e., transaction complete.

Impressively, not only do iZettle and SumUp turn on within a few seconds, they do something really smart: they automatically turn on when you initiate a sale through the app.

In the period of time between initiating the payment, and grabbing the card reader, it will have turned itself on and probably be ready to use.

In other words; you’ll never need to remember to turn your iZettle and SumUp devices on—you might never even notice that they’ve turned themselves off.

The lift technique hides the loading process of a game, and similarly, turning the devices on automatically right before the user needs them, means that they can power on silently before the user is paying attention. 

By comparison, Square and Verifone have physical buttons that you need to press on the device—so you’ll feel every second of that powering on time, because you’re aware of the process that is going on.

💡 Hidden load times

Lifts are used in video games to mask loading screens. Well, software can pre-empt actions and mask waiting times.

3. The problem with small cables

Ideally, you’d charge these devices every night, and then start each day with a full battery. But, it’s inevitable that you’ll forget every so often.

In those instances, you’ll probably need to use the device while it’s charging, which begs the question; how long is the included charging cable?

Length of the charging cable (cm)






Length (cm)

The average bar counter is about 100cm tall. For a device that’s intended to be placed on a counter, surely you’d make the cable long enough to reach one?

To help you better visualise how short 40cm is, I’ve included the generic iPhone cable (far left) in the image below.

iPhone, Square, iZettle, SumUp, Verifone

This may not immediately seem like a UX problem, but it is.

If your SumUp device ran out of power during a busy period, you’d have to ask your customers to bend down and use their card 40cm away from a power outlet.

Is this why SumUp also sell a ‘charging dock’ with a 1m cable? Probably. Could they have included a 1m cable in the box as standard? Yes.

🌍 Real world usability

It may be cheaper to ship your product with fewer / smaller accessories, but it creates everyday hassle where it's not needed. Hassle = bad UX.

4. The magic of bluetooth

Aside from Verifone, these devices all connect to an app via Bluetooth. This can be an almost zero-click connection process, as shown by SumUp below:

You tap to add a card reader, and it then—somehow—wakes up your device, syncs it with your app, installs any updates and it’s ready to use.

It worked flawlessly, and the simplicity is a triumph.

Credit where it’s due, Square’s is very similar to SumUp’s.

But by comparison, iZettle’s version feels slightly laboured—you need to select which card reader you want to connect, before it’ll start searching for any.

All four of the iZettle devices have bluetooth, and the type of reader even appears on the ‘available readers’ screen—so it wouldn’t be confusing even if you did find multiple types of reader available nearby.

I can’t see why they’d use this device-selection screen, unless it’s actually just masking some technical limitation.

🧙‍♂️ A moment of magic

If you can remove user-input from a process, often it'll feel like magic. Even just removing one click can make a difference.

5. The instruction manual

This study was published in the 1980s, but it’s perhaps even more accurate today than it was back then: most people don’t read instruction manuals

You see, there are two subconscious assumptions that often make reading these paper booklets feel like a waste of time.


Assuming the fastest route

i.e., people assume that they’ll guess the fastest route, in less time than it’d take to read the instructions and then do those steps.


Assuming it’ll be similar to something else 

i.e., they assume that this product will work like other apps that they already know how to use.

So, as a general design principle, your onboarding needs to help guide this impatient user through the journey, assuming that they never bothered reading the instructions.

Which is why I feel like iZettle, Square and SumUp all dropped the ball here—connecting your card reader wasn’t obvious, there was no onboarding and I genuinely had to go back and check the instruction manual for each of them.

Sure, iZettle and SumUp will prompt you to add one, but only after you’ve attempted to make a card payment—despite it being obvious that you’ve not connected a card reader yet.

It’s a total misfire—it relies on people being curious enough to click on an action that they know they shouldn’t be able to do.

This is highlighted in the case studies themselves, which also include some of my favourite memes yet.

Built for Mars

📖 Instruction manuals

People will ignore these anyway, so make sure that your users can learn how to use your products without them.


Aside from the pitiful charging cable, SumUp has certainly been the easiest device to connect.

But all the entry-level devices—except Verifone—have an achilles heel; they need to be connected to an app to work. And if your phone or tablet runs out of power, then they’re entirely useless.

That is unless you purchase either Square’s (£240) or SumUp’s (£99) more expensive devices, and iZettle don’t even offer any standalone devices right now.

However infrequently you’d forget to charge your card reader overnight, well you actually have to remember to charge two devices.

This creates a trade-off:


1. Standalone device

i.e., no dependency on a second device.


2. App and device

i.e., you can then have the benefits that come with the application layer.

And don’t forget, this application layer opens up a whole world of possibilities, and is one of the main reasons why Square, iZettle and SumUp have done so well in the first place.

But what about if you could get the best of both worlds?

This is exactly what Visa are trying to achieve with their tap to phone technology, which allows you to accept card payments through the NFC chip in your mobile phone.

And this is a step in the right direction for a few reasons:

1.  Lowers barrier to entry. Theoretically, services could charge no up-front fees for someone wanting to take payments.

2.  Faster set-up. You could be set-up and able to take payments within minutes, rather than waiting for the device to arrive.

3.  Very flexible. Say you were at a weekend event and your card reader died—you could use this as a great back-up plan.

4.  Immediately scalable. Do you need 10 more devices for a weekend event? No problem, just ask your staff to bring their mobile phones.

But this technology will not replace physical card readers—at least not immediately,

This is for a number of reasons, but perhaps the most obvious is that these devices can physically read a card—i.e., the old fashioned way.

In the long-term, perhaps a 100% contactless payment option won’t be a hinderance, but right now it is. Right now we need to be able to insert and swipe our credit cards.

So if one of these companies has partnered with Visa in the near future to offer ‘virtual card readers’, you’ve heard it here first.

There are 3 more chapters...


Square’s device was 71% cheaper than Verifone’s, and arrived more than 2x faster.


Verifone’s device arrived misconfigured and was unusable for 3 business days.


Switching to Verifone could save you hundreds of pounds ever year.


Verifone are so far behind with their software, that I doubt they’ll ever catch up.

Get future content delivered straight to your inbox