What is an API? A guide to the Application Programming Interface

Caveat: This is a beginner’s guide. if we tried to write an exhaustive technical guide to the API (or Application Programming Interface), we suspect the internet wouldn’t be big enough.

An Application Programming Interface is a way for different software programs to communicate with each other, allowing them to request and receive services or data in a predefined format. It‘s like a set of rules or protocols for how to “order” and receive information in the digital world.

An API allows any authorised computer programme to access data in a known format and integrate that data into its own processes.

Without being able to obtain specific information or specific instances, the internet would be a nearly infinitely less useful (and entertaining) place. Each time you launch any application on your phone, the app will call an API and check for (for example):

• A news application will ask for the latest news – quite possibly based on your location as you open the application
• Your banking app – ask for the details of your account status and recent banking activity
• Your airline app – will look for forthcoming bookings and tell you what you need to do next (check in, buy insurance and so on).

Based on the data received, the app will build screens and pages into its own interface for you to read and use.

Without access to an API, a news app would be no more versatile than a physical newspaper. You would need to download an updated version whenever you wanted fresh news. Banking apps and travel apps would be entirely useless.

An app may access several different APIs to get to one outcome – for example, a shopping app may check your recent shopping history (match day tickets) and the weather (rain) and suggest you buy an umbrella. This is why some parts of the internet give you the spooky impression they are listening to you (they do that too, but that’s another topic).

As the name suggests, they are devised for applications to use. In fact, you could define the difference between a dynamic website (which refers to its own data) and a web application by whether or not it leverages an API to build the user experience.

APIs can be public (Google Maps) or private (your bank will most likely have one). Securing APIs to ensure they can only be accessed by appropriate users takes considerable expertise.

Because people write APIs for computers (not people), testing and developing with API’s is very much a developer’s job … not every web designer can do it. Developers need to invest time in learning how to use each API effectively, and this learning curve can be steep for more complex APIs. Integrating an API can sometimes be difficult, especially if it involves handling large amounts of data or ensuring real-time performance. This can require additional development effort and expertise.

A well-documented API offers a list of operations (a menu) that developers can use, along with a description of what they do. The developer doesn’t need to know how these operations work internally. Just like you don’t need to know how a chef will prepare your meal in a restaurant, the developer doesn’t need to know the inner workings of the software. A developer just needs to know what requests they can make and what responses the API might return.

So long as the developer can handle the returned data, they can leverage vital information for their application without the need to maintain how they receive it. A developer making efficient use of APIs can rapidly deploy interesting, useful applications.

1. Dependence on External Services: Relying on third-party APIs means your application depends on someone else’s reliability and uptime. If the API goes down or experiences performance issues, your application may suffer as a result.
2. Limited Control and Flexibility: An API offers what it offers, nothing else. If it doesn’t do as you need, it’s useless to you.
3. Data Privacy Concerns: As described above, artful use of APIs can allow applications to make deductions that reveal more about you than you would like.
4. Cost Implications: API costs can grow significantly with increased usage, and budgeting for API costs can be challenging, especially for startups or smaller companies.
5. Versioning and Compatibility Issues: API providers might update or deprecate features, leading to potential compatibility issues. Your application might need regular updates to stay compatible with the latest version of the API.
6. Rate Limiting and Throttling: Because they are public interfaces, APIs can receive a lot of requests in a very short timeframe. Most prevent overly frequent attempts to retrieve data. This can affect the performance of your app.
7. Continuity of Service: Free APIs can and do stop working without notice. Paid ones do too, on occasion.

Because Application Programming Interfaces work in the background, it is tempting to ignore them once implemented. But, in truth, all require regular oversight. Every API implementation must be written with the potential for failure in mind. An API without detailed logging is a recipe for trouble.

In summary, while APIs offer powerful capabilities for enhancing applications, developers need to be mindful of these potential pitfalls, such as dependence on external services, security risks, cost implications, and integration challenges. Careful planning, thorough research, and robust development practices can help mitigate these risks.