To keep up with the constant changes and new trends in technology, developers must continuously sharpen their skills and learn new tools. One of the core skills every developer needs is building and working with Application Programming Interfaces (APIs).
An API is more than a machine-readable interface to data and services — it is a product in its own right. A well-built API should not only work reliably but also be intuitive, well-documented, and easy to adopt. How an API interacts with its users is a major part of whether it succeeds or fails.
The first person to interact with your API is usually a developer. They will naturally prefer an API that is easy to understand and aligned with the technologies they already use. That’s why it’s worth carefully thinking through the decisions below before your API actually goes live.
The Technology/Format/Type Issues
The REST/JSON vs. SOAP/XML choice becomes much easier once you consider your target audience and use cases. If your users are script-oriented developers, REST/JSON is usually the better fit. If strict quality-of-service (QoS) requirements are involved, SOAP and its standards may be the more suitable choice. This decision becomes even more important when your API needs to support store connectivity across multiple eCommerce platforms, each with its own technical requirements.
Want to make developers’ lives easier? Add some hypermedia and save them hours of digging through documentation you have yet to write. If you’re unsure which media format to choose, here are some of the most commonly used ones.
Vocabulary United
Paying attention to the naming used in the data exposed by your API can greatly ease its adoption by end users. Ideally, your terminology should be consistent with other services or platforms your API is meant to integrate with. This is especially true when your API deals with product types and variants across different eCommerce platforms, where naming conventions can vary widely from one platform to another.
Authorization and Security
If you opted for REST/JSON in the previous step, OAuth is a natural fit. Not sure which version to choose? You can find them described here. If SOAP was your choice, SAML or WS-Security are worth considering instead.
You also need to decide whether transport level security (TLS) alone is sufficient. If not, the data exposed through your API should be signed, encrypted, or both.
Versioning
When planning how to version your API, decide whether versioning will be included in the URL or returned in the content-type. For HTTP/REST APIs, your strategy may rely on paths, query arguments, or HTTP headers. For SOAP APIs, it may be based on namespaces or endpoints. It’s also worth thinking ahead about how your API will notify integrated systems of changes — for example, through webhooks for real-time data sync, which can complement versioning decisions by keeping connected systems up to date as your API evolves.
Documentation
Documentation teaches developers how to use your API, so it should be as detailed, unambiguous, and rich in code samples as possible. Documentation generators can help streamline this process. Some of the most reliable tools are listed here.
The points above cover only the basic elements of API design. For a deeper dive into the topic, we recommend Undisturbed REST: A Guide to Designing the Perfect API by Mike Stowe.
Marketing manager, API fan, nerd, perfectionist, British humour enthusiast, literature and history geek.
