The Power of APIs: How They Drive Our Digital World and Why They Matter for Your Software Application

An API, or Application Programming Interface, is a set of protocols, tools, and standards for integrating software applications. In simple words, an API is a mediator that enables different software systems to communicate with each other via function calls sharing data and functionality but remaining independent from each other. Postman, the world's leading API platform, used by more than 20 million developers and 500,000 organizations for building and using APIs, in its State of the API Report 2022, indicates that over 62.6% of developers rely on APIs more in 2022 than they did in 2021. Additionally, 69.2% expect to rely on APIs even more in 2023. Сurrenlty there are over 2 million API repositories on GitHub.

APIs are everywhere in our everyday lives, powering many services such as universal login systems, hotel and flight booking engines, third-party payment processing, and more. For example, social media APIs offered by Facebook, Twitter, and Instagram enable developers to create apps that integrate with these platforms, allowing users to share content directly from their mobile devices. Payment gateway APIs from providers like PayPal enable secure online payment processing for e-commerce websites and mobile apps. Google Maps APIs provide mapping functionality for developers to integrate into their applications, and APIs from services like OpenWeatherMap provide real-time weather information for weather websites and apps. These are just a few examples of the many ways APIs are used in our daily lives.

The adoption of APIs has become ubiquitous across industries, enabling organizations to harness the power of software integration to enhance their offerings, streamline operations, and improve customer experiences. According to the State of the API Report 2022, the technology sector remains the leading industry in active API use. Nonetheless, APIs are not exclusive to tech companies. Every industry has the potential to leverage their benefits.  Certain sectors, such as healthcare and banking, are required to provide APIs as a result of regulations to ensure compliance with laws and regulations. Others, such as telecommunications, are motivated by industry interoperability. Finally, some industries, such as retail, media, and entertainment, adopt APIs as a response to disruption. They use APIs to improve their offerings, streamline operations, and enhance customer experiences in order to stay competitive in a rapidly changing market.

Using both existing third-party APIs and developing your own APIs can be equally important and valuable depending on a software application's specific needs and goals. These two approaches are neither mutually exclusive, nor mutually binding, so developing your own API to integrate it with other software via APIs is unnecessary. 

Using third-party APIs allows developers to expedite application development by integrating pre-built functionality to handle common tasks, such as authentication, database queries, image processing, and more. This approach eliminates the need for developers to create every component of an application from scratch and independently implement similar functionality. And this integration can be done regardless of the technology each project is built in. Integrating with third-party APIs entails greater flexibility and scalability, task automation, cost savings, access to more data and services, and improved user experience. State of the API Report 2022 indicated that the most critical factor developers consider before integrating with an API is performance, slightly outnumbering the previous year's number-one pick, security. Reliability and documentation remained among the top four factors. Also notable are scalability and usability.

Despite the above-mentioned advantages, there are also some potential downsides to using third-party APIs. A significant challenge is a dependence on external services, as developers and businesses rely on API providers who can experience downtime or change pricing and terms of service. Companies have also shut down services and APIs in the past, leaving users without access to necessary data. These challenges can negatively affect user satisfaction and business outcomes by disrupting the functionality of applications that rely on the API. Therefore, it is essential to prioritize careful consideration and planning when using third-party APIs to mitigate potential risks.

When it comes to developing an API for your software application, keep in mind that not every application necessarily needs one. For example, if you are building a web application, having an API can allow other developers to build integrations with your application, such as, for instance, third-party plugins. On the other hand, software applications that do not need to interact with other systems or provide data to other applications may not require an API. For example, a basic calculator app may not require an API as there is no need to exchange data with other systems. 

It's worth considering that even if a software application doesn't currently require an API, it may still benefit from having one in the future as the application evolves and new integration opportunities arise. Building an API can make taking advantage of these opportunities easier and make the application more extensible and flexible. However, developing an API involves development and maintenance costs, as well as a significant time investment, so careful consideration of the costs and benefits ratio is necessary to determine if it's the right choice for a specific application. Choosing a software development company that has experience in building APIs can help you ensure that your API is designed with scalability and future growth in mind taking into account the costs and potential return on investment.

APIs can be classified by the systems they are designed for:

• Database APIs: are a type of API that allows developers to access and manipulate data stored in databases, such as SQL or NoSQL databases, through a programming interface. With a Database API, developers can create, read, update, and delete data from a database by making requests to the API. The Database API processes the requests, translates them into the appropriate database queries and returns the results back to the client. It allows developers to build applications that can retrieve data from multiple databases, query and manipulate the data, and display it to users.

• Operating Systems APIs (also known as System APIs): are a type of API that enables developers to interact with an operating system's resources and services. These APIs provide a way for applications to access and control the operating system's resources, such as memory, input/output, and the user interface. For instance, posting a photo on a social networking channel from any device is made easy by the device's operating system API, which enables the social networking channel to request access to saved pictures.

• Remote APIs: are a type of API that allows one software product to access resources located outside the device that makes the request. Since the applications are remotely located and connected over a communications network, typically the Internet, most remote APIs are developed based on web standards. While all web APIs are remote, it's important to note that remote APIs aren't necessarily web APIs. 

• Web APIs: the most common type of API, particularly of remote API, that is designed to allow software applications to communicate and share data with each other over the Internet using web technologies such as HTTP and XML or JSON. Developers use web APIs to extend the functionality of websites or web applications, allowing them to integrate third-party services and data into their own applications or to make their own application's data and functionality available to others via the Internet. Usually, when speaking about APIs, it is Web API that is referred to.

Web APIs are further classified into four main types based on their release (audience) policies according to the intended level of access and scope of use:

1. Public APIs: These APIs are available to the public with no or minimal restrictions on usage. They can be open, free of charge, with all features available for use without any restrictive terms, or commercial with subscription fees or pay-as-you-go pricing. Examples of such APIs are Google Maps API, Twitter API, OpenWeatherMap API, etc.

2. Partner APIs: These APIs are exposed to strategic business partners and unavailable to the public. Specific entitlement is required to access them. Salesforce Partner APIs, eBay Partner APIs, Amazon API and AWS Partner Network (APN) APIs are examples of APIs in the category. 

3. Internal APIs: These APIs are only available for internal users and internal systems within an organization to enable, for instance, different departments to share data, different modules to communicate with each other, to access backend systems or databases, automate internal workflows, for testing or debugging purposes during development, etc.

4. Composite APIs:  These APIs combine data and other APIs on multiple levels and enable the simultaneous execution of multiple processes through a single API in a synchronized manner, i.e., access to several endpoints in a single call. A typical example of a composite API is any aggregator site that combines several different APIs, such as flight search, hotel search, car rental search, price-comparative search, etc.

Web APIs can be found on either open API marketplaces, where anyone can list an API for sale, or controlled API directories, where expert API designers may assess and test new APIs before adding them. Some popular API websites like Rapid API and APIList offer access to thousands of public APIs, categorized for easier browsing, and provide in-depth information on how to use them.

In terms of architecture, APIs can also be divided into different types. The main differences between these architecture types are in how they handle requests and responses, the format of the data they return, and the level of flexibility they offer. The two main subgroups are request-response and event-driven types. Event-driven technologies Webhook, Websocket, and Server-sent Events differ from request-response models like REST or SOAP in their ability to transmit information in quasi-real-time. They excel in cases like stock market trackers requiring constant data updates or IoT devices monitoring real-time events. The event-driven architecture allows the source to send a response only when the information is new or has changed, avoiding unnecessary back-and-forth communication. Event-driven APIs have gained traction in recent years due to their ability to solve specific pain points and use cases in our data-intensive, always-on world. 

State of the API Report 2022 revealed that although REST remains the most widely used API architecture, it has slightly decreased in popularity compared to last year, with 89% of respondents selecting it. REST is typically simpler to implement and has wide industry adoption, while SOAP offers more features and is better suited for complex enterprise applications. GraphQL is relatively new but offers significant performance advantages over REST in certain use cases. Besides, newer types of APIs, such as Webhooks, GraphQL, and gRPC have gained popularity, with 35%, 28%, and 11% of respondents using them, respectively. As technology evolves, these new types of APIs are expected to continue to grow in popularity.

Here are more details about the most popular architectural styles mentioned above:

1. REST (Representational State Transfer): a stateless architecture that uses HTTP methods to create, read, update, and delete (CRUD) operations. It typically returns data in JSON or XML formats. These are the most popular and flexible APIs found on the web today. The client sends requests to the server as data. The server uses this client input to start internal functions and returns output data back to the client. 

2. Webhook: event-based type of APIs that allows a web application to send real-time information to another application. In simple terms, webhooks are automated messages triggered by events and sent from one system to another. They are sometimes referred to as 'reverse APIs' since they enable one system to check for changes in data in another system. Webhook APIs are commonly used in scenarios requiring real-time data transfer, such as chat applications, social media platforms, and e-commerce systems. 

3. SOAP (Simple Object Access Protocol): an XML-based messaging protocol that uses a contract-first approach, which means the API client and server must agree on the data format before communication can begin. It is more structured and formalized than other APIs and was more popular in the past before REST came to the scene.

4. GraphQL (Graph Query Language): a query language that allows clients to request specific information or only the data they need instead of relying on endpoint definition. In traditional RESTful APIs, clients often receive more data than they need, requiring additional processing to filter out unnecessary data. With GraphQL, clients can specify the fields and relationships they require in a single request, reducing network traffic and improving performance. GraphQL has gained popularity in recent years, particularly for use with mobile and web applications, due to its flexibility and efficiency.

5. Websocket: a bi-directional protocol allowing real-time two-way communication between a client (such as a web browser) and a server. WebSocket APIs are not based on the request/response model but rather on a continuous connection that can be used to send and receive data in real time. It makes them ideal for applications that require real-time updates, such as online gaming, chat applications, stock market data, and more.

6. gRPC: a modern open-source high-performance Remote Procedure Call (RPC) framework that can run in any environment. It allows a client to call on a server like it's a local object, making it easier for distributed systems to communicate. With gRPC, developers have the flexibility to define custom function calls instead of being limited to predefined options such as PUT and GET.

7. MQTT (Message Queuing Telemetry Transport): a messaging protocol a lightweight publish-subscribe messaging protocol designed for use in constrained environments such as low-bandwidth, high-latency, or unreliable networks, and is often used in the context of the Internet of Things (IoT). It enables devices to send data as small messages to a server, which can then be transmitted to other devices or applications that have subscribed to receive them. 

8. AMQP (Advanced Message Queuing Protocol): a protocol that follows open standards for passing business messages between applications or organizations. It is used in various applications, such as financial services, healthcare, and telecommunications, where message delivery and reliability are critical. 

9. SSE (Server-Sent Events): a technology enabling a server to push data to connected clients automatically, without the need for the client to request it. It is based on a unidirectional, long-lived HTTP connection that allows the server to send messages to the client whenever new data is available, so a client can automatically receive updates without repeatedly polling the server for new data.

10. EDI (Electronic Data Interchange): a standard format for exchanging business documents electronically between different companies' computer systems. EDI APIs facilitate the integration of EDI systems with other applications and services, allowing businesses to exchange electronic documents in a standardized, automated way. EDI APIs often provide functionality for converting documents from one EDI format to another, as well as validating and processing EDI documents for various business transactions such as orders, invoices, and shipping notices.

The report also indicates that among the most popular API tools and platforms developers use is Postman. Postman is a software tool used by developers and API providers to test, document, and debug APIs. It provides a user-friendly interface for sending HTTP requests, inspecting responses, and organizing API requests and responses. Postman can be used for testing both RESTful and SOAP APIs, as well as other web-based APIs. It gathers mentions from 89% of respondents. SwaggerHub, the platform for defining, visualizing, and validating APIs in a collaborative environment, gathers 24%, While Insomnia, a free, cross-platform desktop application that simplifies the interaction and design of HTTP-based APIs, gathers 10% mentions, respectively.

In conclusion, APIs are a crucial part of our digital world, and they are becoming increasingly important to developers and businesses. They are transforming the way we construct modern digital solutions, providing the fundamental building blocks from which they are built. Companies can leverage existing APIs to create new products and services while also contributing new APIs in return. Technology is now an essential aspect of any business, enabling seamless integration of new applications with existing software and facilitating system interoperability. APIs have already revolutionized numerous industries by facilitating new business models, streamlining workflows through secure and efficient data exchange, and unlocking new opportunities. As more industries adopt APIs, we can anticipate even more innovation and transformation in how businesses operate. 

Reading time 10 min 37 sec