Principles of Web API Design
21 Jun

Principles of Web API Design

Mahipal Nehra

What are the Principles of Web API Design? APIs have been around for decades. In the early days of APIs, they were libraries and components shared across an organization. With the rise of SOAP and COBRA, APIs became distributed components that could easily integrate with distributed services. They were built for interoperability but lacked effective design requiring months to get successfully integrated.

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Once Web APIs replaced these standards, there was only a need for a few APIs. The development team can take time to design APIs and iterate as required accurately. There is no such need anymore. The reach of Web APIs now goes beyond just internal partners and systems.

Web API (Application Programming Interface) is an interface with sets of functions that allow programmers to access some features or data of an application over the web using the HTTP protocol. Web API is a framework to help developers to build RESTFul services based on HTTP. It can be developed using different programming languages like ASP.NET, Java, etc.

Read: What is an API and How it works

Web APIs can connect organizations to their workforce, customers, and partners using the web standards. With Continuous Integration and Continuous Delivery tools, it has become easier to build automation pipelines to deliver APIs swiftly and efficiently.

However, one of the main challenges that still need to be addressed is creating successful APIs that can be integrated and understood easily by developers.

In this blog, we will find the best practices and principles of web API design. So, let’s get started!

Elements of Web API Design

The Elements and Principles of Web API Design. APIs provide a view into the marketplace business value of an organization. Everything offered (and not offered) in an API speaks volumes about an organization. The three important elements that an effective Web API design will include are business capabilities, developer experience, and product thinking.

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So, let’s take a look at each of these elements of web API design.

  • Business Capabilities

Business capabilities refer to the enabler an organization brings to the marketplace. It can include both internal and external capabilities such as credit risk assessments, sales pipeline management, unique customer service, optimized product design, and product delivery.

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These capabilities can be delivered directly by the organization, via a blend of third-party and organizational processes, or outsourced through a third-party provider. And APIs digitize these business capabilities to a marketplace.

So understanding the underlying business capabilities is crucial before designing the API that will reflect them.

  • Thinking about Product

Implementing product thinking in the process of designing API transfers the focus of the team from a single partner to designing an effective API that can handle automation possibilities with minimal customization effort for a certain segment of customers. This also allows a self-service model for customer-driven, business-to-business, and workforce integration.

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With less concentration on custom implementations of APIs and more on meeting market needs, developers can make APIs more cost-effective and scalable. While focusing on multiple customers at once, one can also design reusable APIs.

By obtaining feedback from multiple stakeholders that will use the API, developers can shape the API design and increase reuse opportunities.

  • Developer Experience

As important as UX is for products and services, developer experience (DX) is important for APIs. DX focuses on different engagement aspects of developers for an API product and extends beyond APIs' operational details. DX also includes all aspects of API whether it is the first impression or its regular usage.

To build a successful API, it is important to have a great Developer Experience. With a good DX, it becomes easier for developers to understand and use a Web API while improving the traction in the market for the produced APIs.

Read: Why Web Designing important

As API teams seek to understand how they can design a great experience for the API, it is essential to remember that developer experience is also a critical part for internal developers.

For instance, well-written documentation allows developers to understand and use the API instantly while with poor documentation it becomes quite difficult to learn to use it properly.

Principles of Web API Design

What are the Principles of Web API Design?  An API design approach must have a balance between higher developer experience and robust digital capabilities for quick and easy integration. So it must be rooted in a series of foundation principles. These principles of Web API designing are:

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  • Never design an API in isolation. Collaborating API design is good for building efficient API.

  • To create an API that delivers value to every user, it should be designed with the outcome as a focus.

  • Always choose the API design elements that match the requirement, whether that is gRPC, REST, or GraphQL.

  • API documentation should be the priority rather than left as a last-minute task because it is an important interface for developers.

  • Thoughtful API design combined with an evolutionary approach to design makes APIs resilient.

  • Stateless: The APIs should communicate in a stateless manner in client-server applications. All the information must be contained in the client request to the server to make it easier to understand. Session state should therefore be kept on the client-side completely.

  • Client-Server: The principle behind the client-server constraints is the concern of separation. Simply, by separating user interface problems from data interface problems, it becomes easy to improve the portability of the user interface across different platforms to improve scalability and simplify server components.

  • Cacheable: Add constraints to create client-cache-serverless-server and improve the efficiency of the network. These cache constraints make the data respond with the explicit or implicit label as non-cacheable or cacheable to a request. If the response turns out to be cacheable, the client cache is then allowed to reuse the data response with similar requests when needed.

  • Code-on-Demand: Web APIs allow client functionalities to increase by executing and downloading code in the scripts or ample format. Minimizing the number of features to be pre-implemented, simplifies the client-side and improves the extensibility of the system.

  • Layered System: A client API can never tell if it is connected to the end or intermediary server in the path. However, adding layers and intermediary servers can enforce security and improve the scalability of the system by allowing load-balancing and shared cache.

  • Uniform Interface: Adding the software development principle of generality while developing Web API to the component interface can make the entire system architecture simple and improve interaction visibility.

ADDR Process

ADDR stands for Align, Define, Design, and Refine. ADDR is the four-phase process that every developer goes through when designing and developing an application interface programming (API).

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Developers might not do it intentionally but they start from scratch by going through the requirements like what the API must be doing, and aligning on that. Then we move ahead by defining the API and applying the ideal API style while designing and finally spend time to gain a lot of feedback from the user.

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Sometimes we have to write a lot of code and other times work in parallel with them or do coding alternatively, but it is important to recognize that APIs are also forever. Another thing to keep in mind is that after making a contract API is not like code. APIs are located in the shared library and when we want to make some changes or coordinate with internal developers, it can either make or break the API.

APIs are not something we can run some unit tests on and determine the errors because more often than not most of the errors are external and outside of control. And that’s why we have to fix the contracts when required. Developers can add to APIs, and enhance them but can’t break them as we don’t want to provide a poor experience to the consumers.

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Hence, the ADDR process is designed to help developers to go from requirements to designing an API they are sure of finalizing the code for. Although it doesn’t mean that parallel coding or prototyping risk mitigation is not allowed to explore technical solutions, we need to be careful not to start writing, designing, and delivering API that we haven’t given much consideration to as it can lead to a lot of errors and breaking connections between APIs. Otherwise, at the last moment, one has to make quick changes further complexing the task at hand.


Now that we know about the basic principles of web API design, we shall keep in mind some of the best practices as well. Some of the best practices a developer should follow are:

  • Keeping API simple and fine-grained that can utilize different underlying resources in the system while reducing excessive communication between APIs.

  • Versioning APIs so that in case something goes wrong you can switch back to the previous version in an instant.

  • Filtering and Ordering API to make it easier to search specific query values and sort the response data.

  • Allowing the layered system to remove remote calls and give requested data as a response by caching to increase scalability.

  • Adding security and monitoring to improve the quality and performance of APIs.

So that was all about Web API Design principles, we hope it will be helpful for your future project as a developer.

Read: API VS Web Services VS Microservices

If you are a business owner who wants to build a web app based on web API then you should hire developers from companies like Decipher Zone Technologies with relevant experience and expertise.

Posted by Mahipal Nehra | Posted at 21 Jun, 2022 Web