When designing your mobile app, you can integrate APIs to make your app more functional and efficient. APIs, or application programming interfaces, connect your application to other applications. They allow different systems to securely and swiftly communicate information. They open up your functionality and data so that you can share it with others. This increased openness can drastically improve your app.

Common Uses of APIs

APIs are often used in apps to integrate phone functionality with in-app actions. Some of the most common integrations are with text messages, phone calls, phone camera, GPS, email, payment processing, and calendar. For example, Uber uses the Google Maps API to power its GPS system and the Braintree API to process its payments. Instagram uses the Foursquare API to allow users to tag locations in their posts. APIs are also commonly used for data caching and shipping functionality.

Build vs. Buy

You can either integrate existing APIs into your app or create new APIs yourself. Each approach comes with its benefits. Integrating an API is usually cheaper and faster, but creating your own API allows you more power to customize your API and ensure its security.

If you choose to buy an existing API to integrate into your app, try exploring sites like RapidAPI.com and ProgrammableWeb to understand your options. If you choose to build an API, make sure you either use in-house talent or external engineers whom you can trust. If you’re not sure which approach is better for your business, try using this build vs. buy calculator to make a more data-driven decision.


If you do decide to build your API, consider using common architecture. The common architecture will be more familiar to most developers, which will make the building process much more smooth. It will also be helpful in the future if updates are needed, as developers will more easily understand your API’s architecture.

While designing your API, you may run into four types of architecture: pragmatic REST, web service, hypermedia, and event-driven. Pragmatic REST is generally good for mobile apps but may be hard to adapt to future technological changes. Web service is not a good choice for mobile apps, although you may come across it as you design your API. Hypermedia is used more often for the web than mobile apps but can work well with APIs. Unfortunately, most developers don’t know much about this architecture. Event-driven can be a cheaper option, although it isn’t always sufficient for API design.

Develop Permissions

You should build a developer key into your API so that anyone who uses it has to plug in the private code to use the API’s functionality. This keeps users from abusing or hacking the API. You don’t want to worry about people intentionally breaking the API by spamming it with requests, for example.

Document Your Development

Clear, information-rich documentation is an integral part of API development. Documentation helps you track the progress of your own work while reducing barriers for later editing and API sharing. If you bring in an engineer later to repair an API and your past documentation isn’t clear, you risk frustrating them. It will be more difficult for them to understand the API’s history and current state. Most likely, it will take them longer to repair your API and will end up costing you more. Moreover, documentation helps you open up your API to share with external developers in the future. If you want other apps to use your API, enhancing its power and reach, you need external developers to understand how it works. Clear documentation and information-rich snippets of code enable you to show off your product.

Plan for Change

Eventually, you will need to update your API. You should consider how you will approach that change sooner rather than later. While development and change are generally good, you have to handle API versioning with care. You not only imperil your API; you also endanger all the applications that rely on its functionality. What’s more, the best practices for API versioning are highly subjective. There is no external body or consensus that can guide companies. Instead, best practices have to be determined case to case by businesses focusing on what’s best for their own products. Evaluate your business, products, app, and API, and use that information to plan a versioning strategy sooner rather than later.


APIs have the potential to take your mobile apps to the next level. Whether you purchase an API or build one yourself, APIs offer your business a host of benefits.