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What is an Open API and Areas Where It is Actively Used?

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Recently companies competed with each other by the number of branches. In the future, they will most likely compete in the functionality provided by the API of their systems. After all, it is already clear that the Open API is being included literally everywhere, becoming a natural part of the world of technology and business – both in the virtual world and in the real one.

The Open API is a publicly available set of software tools that enable communication between applications. Thanks to open interfaces, third-party developers can access a specific resource’s functionality and content and use it, for example, for partial integration or creating their applications.

In order to offer users the most modern digital solutions, such as typical applications through which it is convenient to make payments, direct cooperation with banks is essential for developers. And it is done using the API. This tool allows, upon the client’s request, to exchange information between the bank and the developer’s application.
Today the API functionality is continuously being supplemented and improved. And this abbreviation – API – is now increasingly seen by customers, mainly entrepreneurs when it comes to different products and banks, modern fintech companies, or online commerce.
As with any business, there are specific standards for using the API that provide a common framework of communication and development and ground us in picking the right tools based on a particular need.

The standard for API definition in the RESTful API world is the OpenAPI Specification (OAS). OAS, based on the original “Swagger Specification,” has gained immense popularity in API development among thousands of API developers and consumers.

This is all a result of the fact that APIs allow businesses to build and scale their business faster and set strategic and business goals by integrating and consuming third-party services for overall revenue and growth. The new age of REST APIs, unlike their predecessors, is not data-driven, but consumer-driven.

Accurately-designed APIs help solve a real consumer problem, and that’s where we see the main focus in APIs from companies like Dropbox, Stripe, and eBay. Reusable interfaces based on HTTP standards are now required by many companies that enable the reuse of data and functionality built for consumer demand and self-service.

Enter the OpenAPI Specification

The OAS is to REST what WSDL was to SOAP. It provides a common framework for designers, developers, testers, and DevOps to build and maintain APIs. The specification as a set of rules to build and introduce a REST API. The OpenAPI Specification is readable for both human and machine, that means you can understand the capabilities of a service without requiring access to source code, additional documentation, or inspection of network traffic.

Since we already found out that specs can help develop consumer-oriented APIs, let’s figure out how to use a spec in the development lifecycle?

OpenAPI-Driven API Development

API-oriented development means an API’s interface will be designed with the granularity of requests and responses that will first expose your API endpoints only after you may start building the API business logic, testing the API for bugs or defects or any other life cycle function.

Benefits of an OAS-Driven Approach

The API-centric approach provides a number of benefits that are directly related to the consumer-centric approach to API development.

  • Better development experience. Good development experience for using APIs is critical in a hyper-competitive API ecosystem. You can focus on the needs of the API user ahead of time. This allows you to take a developer-centered approach and ensure that your end-users’ needs are met in the best possible way.
  • Enables Independence. The approach reduced dependencies between different teams working on your API, like the front-end and back-end teams, or the architects, tech writers, and QA. This is because the definition of the API keeps various stakeholders aligned on what the API is supposed to do, and how it relates to their job function. It acts as the contract between the API’s intended service and its functionality and ensures more accessible communication.
  • Faster go to market. Since dependencies are removed, different teams can perform their functions at a much faster and efficient rate. The hand-off process between teams is significantly easier, making your APIs release much quicker.

As we already said, many business areas use the capabilities of the Open API and OAS-driven APIs for important tasks, but the industries most actively using it are banks and financial and technical organizations, e-commerce, and media. Let’s see real examples.

  • E-commerce is one of the leading industries of the OpenAPI beneficiaries. Commercial companies can scale their services so quickly and thus satisfy their customers. eBay uses OAS to provide API contracts to interested developers. These contracts serve as a point of reference for new applications that will consume eBay’s APIs. Thus, e-commerce is attractive enough to develop OAS-driven APIs, which is beneficial for entrepreneurs in this area.
  • The OpenAPI specification is also widely used in the media industry. One example is social media giant Twitter and its developer platform for open APIs. The Twitter platform is defined using the OAS and offers several public APIs that third-party sites and application developers can use for themselves. If you visit a website or blog that allows you to share information via Twitter, it’s all thanks to this OpenAPI-based mechanism.
  • The banking and finance sectors are interesting examples of Open API implementation. Until recently, financial institutions were wary of using open APIs due to security risks. But modern APIs are designed to be even more secure. Public APIs operated by OAS has won the trust of banks and financial institutions in a short space of time. This is manifested in the growth of “open banking” or the availability of general banking services made possible by an open API.

According to the directive of the European Union on the Provision of Payment Services of September 13, 2018 – banks are required to provide Open API to expand competition in the payment services market. Also, it is designed to protect consumer rights better when shopping online, encourage the development of payment systems, and secure payments, to strengthen support for startups, banks will be required to implement interfaces for payment service providers to access customer accounts.

The modern API no longer follows the traditional data-centric view. Applications, both software and hardware, are plugged in, and APIs are at the center of this digital revolution. For these apps to connect, we need real developers to understand what your API is doing, which is why a consumer-centric view of the API is rapidly gaining popularity.


The Open API is a publicly available set of software tools that enable communication between applications. Thanks to open interfaces, third-party developers can access a specific resource’s functionality and content and use it, for example, for partial integration or creating their applications.
In the Open API, customer data is more than secure. Each user himself determines which data can be accessed and transferred to third parties, and which cannot. For example, fintech creates comfortable services based on Open API systems for payment and cost control, as well as the customer’s entire financial history. The open standard API guarantees complete data security.
The whole concept of an open API that has restrictions may sound absurd, but in reality, it is not. An open API can be accessible to the general public and can also be invoked from any place on the internet. A private API can’t be accessed openly via the internet. It requires access via a set of restricted API calls through a firewall or perhaps a VPN service. Since closed APIs are held in highly secure servers, they don’t employ strict user authentication because it implies that the user makes that call is in the trusted realm. Also, closed APIs fit internal services and processes. On the other hand, open APIs are more focused on delivering user based capabilities and services.

The OpenAPI Specification helps you create APIs that meet business needs while providing an excellent development experience with a definition-driven approach.

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