Back to Blog

Code First vs. API First: Choosing Your Path

API development is a critical aspect of modern software engineering. Two popular methodologies dominate the field: Code First and API First. Understanding the differences between these approaches can significantly impact your development workflow. 1

Code First Approach

The Code First approach involves writing code before documenting it. Developers typically use this method to build the API's models, methods, and data access layers. Then, they generate API documentation from the code. 1

This approach is beneficial for 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. It might be a good approach for rapid prototyping, small teams, or projects with highly iterative development. 1 4 9

However, the Code First approach has its drawbacks. It can lead to bottlenecks as developers follow a waterfall model to API development, leading to sequential work rather than parallel work. 7

Moreover, it can be challenging for other stakeholders like QA and the front end to understand the API without understanding the code or working with a Business Analyst. 4

API first by
Image credit

API First Approach

The API First approach, also known as Design First, starts with defining the API specification before writing any code. Tools like OpenAPI, Swagger, or RAML are used to create a contract that describes the endpoints, parameters, responses, and errors of your API. This contract serves as a blueprint for your development, testing, and documentation. 2 4

The API First approach promotes collaboration between different teams, such as developers, testers, and stakeholders, as they can provide input and feedback on the API design 9

It keeps everyone on the same page, allowing testers and technical writers to 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. 1 7

However, the API First approach may require more time upfront for planning and designing the API specification, which could slow down the initial development process. 9.

Choosing the Right Approach

The choice between Code First and API First depends on your project's specific needs. Code First may be more suitable for smaller or simpler projects, where the requirements are not well-defined or may change frequently. 9

n the other hand, API First is beneficial for complex projects and large teams requiring collaboration. 9

In conclusion, both Code First and API First have their strengths and weaknesses. The key is to understand your project's requirements and choose the approach that best aligns with your team's capabilities and the project's goals.