APIs have usability, too!

Usability has a long history in software. In fact, as I sat down to pen these words, I googled "history of usability ux" and turned up some scholarly articles going back over 100 years. Too far. In software, you can't go wrong starting with Apple, which puts the origin of UX in the mid 90's. Better.

But for much of this time, we've tuned in to software usability as experienced through our user interfaces by end-users. Today, there's more to usability than user interface design, and I'd like to broaden the discussion a bit.

Usability? What usability?

When you think about great user experiences, typically, we don't consider them to be great user experiences unless we start comparing them to lesser experiences. I believe this is a big clue into how we can apply UX more universally. I really think a lot of usability boils down to doing what a user is expecting you to do... so when you do it, most users will never even notice.

Think about it - when's the last time you gave a passing thought to usability for an application that was already behaving the way you wanted? There are scores of great books on how to achieve usability (I love Steve Krug's Don't Make Me Think, and Don Norman's The Design Of Everyday Things), but I really believe if you can manage to do what the user is expecting you to do, you're typically in pretty good shape.

The changing landscape of applications

Next, let's look at changes in applications and application design. You can probably see where this is going. Whereas once the only users of our applications were end-users operating via a Windows or web interface, cloud-native applications based on microservice architecture rely heavily on APIs to orchestrate, integrate and extend functionality. In many cases, APIs are the interfaces for services, and developers are our users. In this sense, APIs are the interface, and the user experience (UX) is found in the ease-of use of these APIs.

And what is it about an API we'd consider more usable? As with the generalized case above, I think the ultimate yardstick is whether the API behaves the way a developer would expect. I believe the popularity of RESTful APIs, for instance, isn't just because JSON is easy to work with -- it's because a well-written RESTful API is discoverable and predictable.

Note that discoverable isn't the same as documented - even correctly documented, which never happens. Discoverable starts with tools like swagger that expose live documentation of API methods and objects, but it connects with predicatable in an important way: as developers engage with your API and discover how some of it works, consistent behavior and naming creates predicability. When these two factors are combined, they reinforce one another and create an upward spiral for developers in which learning is rewarded and also helps future productivity. And yes - this exact relationship is part of understanding usability in a visual / UX context, as well.

Watch for more posts on API conventions and style soon, and watch for the ways these ideas support one another and ultimately contribute to Krug's tagline: Don't make me think!

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