The personal website of Matt Henderson.
07 September 2016
In the world of web application development, we sometimes face technical decisions whose trade-offs extend beyond the technical. Those non-technical trade-offs can be subtle, and perhaps difficult to identify, yet critical to the business. In this article, I want to highlight as an example my experience with the TransferWise payment system, in which technical decisions ultimately work contrary the core of the product.
In the early days of web applications, browsers like Firefox and Safari could only render web pages whose contents were structured in HTML and possibly styled with CSS. Any “logic” that formed part of the application had to be executed on the server. Whenever you clicked a link on a screen, you’d experience a page refresh as the browser sent the request data back to the server, waited for the server to perform any necessary checks and calculations related to the request, and then your browser would display the HTML/CSS that was returned by the server. So in those days, your browser only displayed things; any “thinking” happened on the server. Time progressed, and browsers gained the ability to execute JavaScript software, thereby opening the door to implementing “logic” that gets executed within the browser client itself. One of the most common first uses was in signup forms, as the browser could check that your entered-twice passwords matched, without requiring a page refresh and request to the server application. Things got even more sophisticated when the browser could make a server request that’s transparent to the user. You’ve probably seen that when entering your username in a signup form, seeing a small spinner appear to the right, followed by a green checkbox informing you that, “Yeah, that username is still available!” As “front-end” technologies continued to evolve over the years, we’ve gotten to the point where entire web applications are implemented in JavaScript, and run within the browser. So, today, a fundamental decision to be taken by a developer when he or she implements a web application is:
Should I implement this logic on the server, or in the client?
The argument I want to make in this article, is that often this decision should be taken by the organization, and not simply left to designers and developers.
The benefit of using client-side logic is generally a smooth and seamless user experience, since the user doesn’t have to wait for page refreshes. The trade-off, however, is the risk of bugs in the user interface, since the JavaScript and rendering engines between different browser (and even different versions of the same browser!) can vary considerably. There are some application contexts in which the risk of interface bugs is compensated by the value of a seamless and interactive user interface:
At the same time, there are some application contexts in which a seamless user interface does not compensate the risk of exposing the user to interface bugs. And, here, I want to highlight an example of a company that has absolutely taken the wrong decision in this regard.
In the past, it was terribly expensive for me to pay European contractors from my American company. First, the transfer itself would cost about $30. But then, I’d lose over 3% with respect to the market rate when the bank would convert my USD source funds to the destination currency of Euro. TransferWise completely disrupted the market of moving and transferring money internationally, charging a fraction of what banks charge. They do this by taking advantage of volume to avoid even having to make transfers, i.e. if Customer A in the US transfers $100 to someone in Europe, and Customer B in Europe transfers the equivalent of $100 to the US, TransferWise can make the two transfers happen simply through off-setting accounting entries, using Customer A’s money to pay Customer B’s recipient, and vice versa.
So what is the TransferWise “product”? If you ask me, it’s the saving of tremendous time and costs when making an international transfer. And here’s where TransferWise have really messed up. They additionally view their “product” as the experience of making a transfer, and from a front-end technology perspective, they have decided that a slick user interface compensates the risks of exposing their user to bugs associated with the heavy use of front-end technologies. To be specific: The process of making a transfer with TransferWise involves five steps:
Looks simple enough, but there’s quite some logic that has to happen:
So the process of initiating a transfer can get surprisingly complicated.
Well, TransferWise decided to implement the entire workflow in one single web page, in which each step in the process is contained within its own component, that opens and closes accordion style. The consequence of this approach, as opposed to pushing all the logic and checks to the server in page refreshes, is that during the entirety of my use of TransferWise, over the past few years, I have ran into user interface bugs probably more than 50% of the time. And sometimes we’re talking about showstoppers—i.e. bugs that, in the name of a slick user experience, actually prevent me from making a transfer! For example, the day that the confirmation button simply wouldn’t activate. Or the day when state wasn’t tracked across components and the confirmation button didn’t provide on-click feedback, such that multiple clicks of the confirm button suddenly skipped you multiple steps ahead in the process, leading to all sorts of chaos.
I use TransferWise once a month to pay my European contractors. Since the only thing that changes each month is the amount I pay to each, I could really use “payment templates”. But since those don’t exist in TransferWise, the next best thing is to click “repeat payment” on some previous transfer, and then change the amount. But it would seem that this isn’t the intended purpose of “repeat payment”, since clicking the option takes you directly to the confirmation component of the transaction screen. You can click back into Step 1, in order to change the amount, but I suspect my particular use of this feature is what caused me to see this, when finally returning to the confirmation component: Try what again? Going from Step 3 to Step 4? Everything looks fine. What’s the problem?! Neither refreshing the page, nor clicking “Confirm” removes the error message or allows me to proceed As with most of these UI errors at TransferWise, it would appear that I’ve reached a dead end. But, in this case, guess what? When I return to my accounts page, I see that the transaction was successfully processed. So the error I was shown—i.e. the one that blocked the whole process—is itself erroneous!
So let’s backup and think about this.
Of course, it’s not impossible to have a reliable application that’s front-end heavy. It’s just that it’s much, much easier to have a reliable application that’s not. And in the case of TransferWise, a slick front-end doesn’t contribute to the core value proposition of the product, and my own experience demonstrates that there’s definitely inadequate value compensation in unnecessarily taking the risk. Conclusion: The very very last thing I want to experience in this context, are bugs that prevent me from making my transfer. For the past year or so, each time I’ve experienced a UI bug, and have reported it to TransferWise, I’ve also take nthe opportunity to encourage them to reduce their dependence on front-end technologies, and give priority to making the process of creating a transfer as reliable as possible. But each time, missing the forest for the trees, their team have instead focused on trying to track down the particular bug I’m reporting (Have you tried that in Chrome?) And so my hope is that through publishing this article, the larger issue might cross the radar of someone in TransferWise management, who’s in a position of considering the broader product goals.
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