What is API?
API, or application programming interface, is one of the essential technical terms in programming. It signifies a documented interface that allows applications to exchange information and use each other's data or functionality to work.
API is a common approach to organising a client-server architecture. The client part is a user interface, and the server is an application that implements an API through which the client can interact with it.
Nowadays, this technology powers most digital products and services. It allows hiding the system's internal details, exposing only those parts that other developers may find helpful. This way, APIs allow companies to give access to their resources while maintaining security and being fully in control.
If that interpretation of the API meaning sounds a bit complicated to you, here's a second definition simple enough to get the gist of it. API is a set of rules for communication between systems. For programmers, APIs are like building blocks with which they can create new programs.
How does it work?
Let's take a look at how an API works step by step:
- A client application makes a request. In other words, it initiates an API call. The request includes a request method, headers, and, if necessary, a request body. It is processed from a client application to the web server via the API’s Uniform Resource Identifier (URI).
- After receiving a valid request, the server application which implements API processes the request.
- The server sends a response to the client application. The response includes header, content, and code (1xx — system's codes, 2xx — success codes, 3xx — redirect, 4xx — client errors, 5xx — server errors).
Types of APIs
By access policies
- Private, or internal — not available to third parties without authorisation, intended for the company's developers to improve the quality of services and goods.
- Public, or external — publicly available interfaces that do not have access restrictions and that third-party programmers can use.
- REST (RESTful) API — REST means representational state transfer. It uses the JSON format. It is the most widespread type, thanks to being reliable, scalable and fast API.
- SOAP — the abbreviation stands for simple object access protocol. It requires strict rules, uses XML to transfer data, and is not able to cache.
- XML-RPC — XML means an extensible markup language, and RPC stands for the remote procedure call. It is considered simpler than SOAP. RPCs are performed by sending an HTTP request to a server that implements XML-RPC.
- JSON-RPC — works similarly to the previous type but uses JSON instead of the XML format.
- Other API technologies.
By use cases
- Web APIs — enable data and functionality transfer between web-based systems which represent client-server architecture. Mostly, the requests and responses are handled using HTTP.
- Database APIs — power interaction between an application and a database management system. Developers write queries to work with the database.
- Operating systems APIs — on these APIs depends how applications use the resources of operating systems.
- Remote APIs — enable standardised interaction for applications running on different machines. It allows the application on one machine to access resources of a different machine.
How widespread are APIs?
According to the survey Developer Nation conducted in 2020, in which more than 17000 developers from all over the world took part, only 11% of respondents said they don’t use APIs in their work. Among those who do, 69% use third-party APIs, while 20% use only private or internal APIs. These numbers prove that APIs are crucial for the development and IT industry.
As for the most popular API categories, these are location and mapping (37%), payments (36%), and email (34%) APIs.
What is payment API?
API that allows businesses to accept, process, or manage financial transactions is called a payment API. Payment APIs allow businesses to create a consistent and seamless purchasing experience for their customers, as well as enable businesses to support different payment methods, track and analyse transactions, etc. Payment API security testing is performed to detect and eliminate vulnerabilities.
For example, every payment service provider or acquirer has its own API. Corefy integrates these APIs, taking the development hassles off your shoulders. We provide client and server applications that let you accept payments and make payouts in different currencies and through various payment methods. All you need to do is to add a few lines of code to your website. If you already have the client part developed on your side, you can use our unified API to connect all the providers you want. It means no need for API development and integration efforts on your side.
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