Your API is the user interface for your consumers’ developers. It is the first and most important way to access and interact with your product - be it a service or a software component of a reuse library.
In other words: your API is your business card.
API needs to be managed and designed with care. Just as you spend time to design a graphical user interface, you need to invest time to design your API: what it exposes, what it does, and how it grows.
Being the user interface for your consumers’ developers it plays an extremely important role in the developer experience and most often provides a first impression about your product’s quality, in general.
If its sloppy, dirty and rugged, don’t expect your customers to trust in your professional attitude or the quality of the solution you provide.
If it’s too special and extravagant and ignoring every design concept the community has embraced, don’t expect your customers to believe you know what you are doing.
If it exposes internal information that is (or should be) irrelevant for your consumers, they will be distracted, confused and finally turn away from you and your product.
An API needs to be designed to focus on the business functionality of your product - and hide the technical intricacies that distract from it.
A good API will simplify the usage of your product and thus provide a business benefit - this can make the difference between a good and a truly professional product.
A good API is designed for compatible evolution - that allows it to grow over time (which is a natural fact as new features are being developed) and yet stay compatible with its own history.
As such, taking time for the design of a good API will pay off in customers’ trust, developer satisfaction, efficiency and reduced compatibility and maintenance issues.
Good APIs matter. Good APIs help. They help your consumers, and they will help you, too.
Spend time for their design. Request feedback from your consumers and colleagues on it. Do it with care and put yourself in the shoes of those who will use it. And if you don’t, prepare to suffer… 😉