API-First Development: The Strategy of Designing APIs Before Implementing Software

Authored by Praveen Kumar Cherukuru - Senior Manager, Engineering, WaveMaker, Inc.

In today’s digital landscape, APIs are unsung heroes that are driving innovation and connectivity. The digital landscape is moving from the web to modern digital channels like mobile apps, IoT devices and chatbots where APIs are the backbone. Adopting the API-first approach ensures that this backbone is robust, scalable and future-proof.

In the traditional development approach, API development is an afterthought. Conventionally, the focus was on building the core functionality of the application. The process looked like this:

Design the user interface > Create the business logic > Then, if needed, expose some functionality through APIs.

In this process, the development of APIs comes late.

This approach creates several issues when integrating with modern digital channels, such as integration bottlenecks, poor security design when exposing the APIs, heavy payloads, limited reusability, and the need of heavy backend infrastructure for scalability.

Shifting this approach from API-last to API-first solves the above issues, improves collaboration and helps with faster development by adopting parallel development.

What is API-First Development

It represents a paradigm shift of developing APIs first instead of last. In this modern development approach, APIs are designed first using tools like Swagger. Architects and developers create a contract that outlines the app’s behavior and its integration. The design-first approach ensures that the APIs are well-structured, consistent and aligned with business objectives.

Key Steps Involved in API-First Design, Development & Deployment

• API Design and Specification: In this step, the developers design request and response formats of the API endpoints, HTTP methods, authentication mechanism and error handling. There are several tools that help this design process effectively. The most commonly used tools are Swagger Editor and PostMan.
• API Documentation: Post the API Design step, the developer needs to document these APIs well so that other developers can understand these APIs and avoid miscommunication. If the design follows OpenAPI specifications, tools like Swagger UI, and ReDoc help create visually rich API documentation.
• API Mocking: API Mocking helps developers to simulate and test integrations before the development of a fully operational API from the backend. This helps the modern digital channels start their UI development in parallel by integrating with Mock APIs. There are several mock API server tools and developers can choose the respective tools for their needs.
• API Development: Once the proper specification is in place it’s easy for the developer to code the functional or business logic according to the specifications.
• API Testing: Testing helps ensure the API behaves as expected, meets the requirements and handles various edge cases. Each API can undergo different testing stages: functional testing, real integration testing, performance testing, and security testing.
• API Monitoring: After the APIs are deployed, it is essential to monitor the APIs to ensure their reliability, performance and security. API monitoring provides several insights into API usage patterns.
• API Versioning: As the requirements keep evolving we need to update the APIs to cater to new requirements. During this upgrade, the developer makes sure of backward compatibility so that the new upgrades do not impact the existing applications that are integrated with and using these APIs. API versioning helps to resolve this backward compatibility problem.

How to Implement API-First Design In Existing Applications

The biggest challenge faced by many is how to adopt this API-first design principle for existing applications that are tightly coupled with the UI. Over the years, I have faced this question during digital transformation projects. We cannot rewrite the entire application. It requires a lot of time and cost.

The approach that helped me overcome that challenge was beginning with small steps to establish the foundational ecosystem.

• Implement an API gateway layer to expose your existing applications built-in with API authentication with OAuth 2.0 and OpenID Connect Standards
• Take 2-3 small functionalities that can be reused by other channels
• Create or refactor the existing code to expose those functionalities as APIs to channels

By creating this base API ecosystem you can gradually convert your existing applications to API-driven applications.

Designing the Digital Experience Channels

Once the APIs are ready, organizations have the opportunity to create user experience channels, whether web, mobile, or chatbot, that can effectively leverage these APIs to deliver exceptional services. The industry is increasingly adopting low code/no code tools like WaveMaker to accelerate the development of UI channels. By integrating these tools, organizations can rapidly and efficiently bring innovative solutions to their users, enhancing both engagement and satisfaction.

Conclusion

The API-first development strategy is not merely a trend but a fundamental shift in how software is designed and implemented. By prioritizing API design, organizations can achieve greater agility, scalability, and innovation. Adopting an API-first approach can drive significant business value, positioning organizations for long-term success in a competitive digital landscape.