API design determines how different components communicate, making it a cornerstone of many software applications. Generally, developers can choose between two approaches when implementing an API: Code-first or design-first. While both methods have pros and cons, choosing the right one can significantly impact your development workflow.
This article will explore the differences between code-first and design-first approaches, how API exploration fits into each method, and how to choose the best option for your project.
A code-first approach to API development has traditionally been faster, but with new tools, a design-first approach can help both short-term velocity and long-term consistency.
Code-First vs. Design-First
A code-first approach, as the name suggests, involves writing code first and then documenting it after the fact. Developers typically use this approach to build the API's models, methods, and data access layers. Then they use tools to generate API documentation from the code after the fact.
The code-first approach may suit developers with a clear understanding of the API design requirements. By writing code before documentation, they can shorten the time to market and launch more quickly. In particular, it might be a good approach for rapid prototyping, small teams, or projects with highly iterative development.
However, this approach makes it more difficult for other stakeholders, like testers and technical writers, to understand the API. They may have to dig into the API codebase and use API exploration tools to understand how it works rather than referencing a precise API definition to write automated tests or compose documentation.
A design-first approach involves creating a detailed API definition before writing any code. While it sounds more time-consuming, developers can use these definitions – such as an OpenAPI specification – to generate code in multiple programming languages and improve consistency across implementations in a fraction of the time.
More importantly, a design-first approach keeps everyone on the same page. After agreeing upon an API definition, testers and technical writers can work in parallel with developers. In many cases, the result is a faster time-to-market for multiple implementations, more consistent documentation, and more reliable tests.
How API Exploration Fits
API exploration is the process of testing and interacting with an API to understand its behavior and capabilities. For example, testers might use cURL or tools like SwaggerHub Explore to send requests to an API and inspect the responses. Front-end developers might experiment using an API to provide data to their components and deliver a user story.
SwaggerHub Explore is an easy-to-use tool that helps developers interact with and explore multi-protocol APIs. After making a request, you can easily evaluate the response and store the requests and parameters for future use. And on a higher level, it enables you to instantly visualize API data to evaluate its capabilities and limitations before investing in API integration.
SwaggerHub Explore’s spaces make it easy to store APIs and search history. Source: SwaggerHub
API exploration is most helpful when combined with a design-first approach since developers can use OpenAPI specifications to create sample requests and responses for testing during the exploration process. It's also much easier to develop automated tests with a pre-existing API definition while ensuring APIs meet governance constraints.
However, a code-first approach may be more suitable for exploratory testing since it allows developers to prototype the API and test its functionality quickly. It's also helpful when it's impractical to make API design decisions (e.g., the project is at a very early stage where the design will likely experience a lot of change).
How SwaggerHub Can Help
SwaggerHub accelerates API development by implementing OpenAPI-powered design standards. In addition, the platform enables tighter collaboration with editors that enforce style standards and delivers up-to-date interactive documentation.
SwaggerHub accelerates your team's design process while enforcing quality and style consistency. Source: SwaggerHub
For example, SwaggerHub's API Auto Mocking integration creates and maintains a semi-static mock of your API based on your definition. And it's updated each time you save your API. That way, developers can test the API when designing it before implementation. You can even start building client applications before the backend is ready.
As you construct an API, SwaggerHub's powerful editor provides smart error feedback and syntax auto-completing based on your OpenAPI specifications to accelerate development. Style validators ensure consistency across multiple APIs, improving the developer experience. And finally, domains make it easy to store, reuse, and reference common syntax across numerous APIs to save time and improve consistency.
When you're ready to launch the API, SwaggerHub Codegen can automatically generate client SDKs, making it easy for all clients to consume the API. You can also produce server stubs to kickstart the development process and cut the time to market. These capabilities help close the gap between a code-first and design-first approach.
And finally, if you've already launched an API, the newly launched SwaggerHub Explore makes API exploration a breeze with support for REST and event-driven API definitions. For instance, developers can send a request and receive an instant response, discovering more about API behaviors and saving time and effort during integration.
The Bottom Line
API design is critical to the success of many software projects. While some teams prefer a code-first approach, new tools make a design-first approach fast and efficient. For example, SwaggerHub lets you automatically mock an OpenAPI specification, generate SDKs, and conduct exploratory testing.
By taking a design-first approach, you can take advantage of tooling, like SwaggerHub Explore, to import and understand the API definitions and kickstart other activities. These efforts can help accelerate the software development process and avoid costly bottlenecks.
Try SwaggerHub Explore for free today.