API First vs Code First: Selecting the Right Approach to Building Products

The ever-growing demand for digital solutions across industries has led to the prominence of two approaches to product development: API First and Code First. Let’s understand the basics of these approaches, their core differences and the key factors that can help businesses make informed decisions.  

The Traditional Code-First Approach 

The traditional code-first approach focuses on writing the code logic first and then designing the API based on the implemented functionality. This approach allows developers to quickly build a functional product and refine their API based on the code.  

The code-first approach allows developers to dive right into coding and focus on implementing the core features and functionalities of the application. This is particularly useful in situations where there is a tight deadline or when the requirements are not fully defined at the beginning of the project. 

However, the code-first approach can lead to a less structured and more difficult-to-maintain codebase. Ensuring consistency and coherence across different parts of the application can be challenging without a well-defined API. Additionally, making changes to the API after the code has been written may require significant refactoring.  

Pros and Cons of the Code First Approach 

Advantages: 

• Rapid prototyping and quick iterations, leading to faster development cycles. 
• Ideal for situations with unclear or changing requirements. 
• Promotes flexibility and problem-solving rather than adhering to a strict design. 

Limitations: 

• Lack of standardized interfaces. 
• Potential for tightly coupled APIs, hindering integration and scalability. 
• Inconsistent designs across components. 
• Difficulty in maintaining a cohesive architecture and documentation. 
• Testing and debugging challenges. 

What is the API-First Approach?  

For many years, the term “API-first” lacked a standardized definition in the industry. The word meant different things to API developers and professionals alike. According to Postman’s 2021 State of the API report, 42% of developers believed “API-first” was about planning and designing APIs and underlying schema before creating other dependent API components and applications. Meanwhile, 31% thought the term referred to building APIs before applications or integrations. While these two perspectives seem similar, there’s a slight difference. The first views API design as a big part of the overall system development lifecycle, while the second sees APIs as the foundation for building other systems.  

As of 2023, this approach has been defined as designing and developing the API before writing the actual code. By starting with the API design, developers can establish clear guidelines and specifications for how different parts of the system will interact with each other. This approach promotes a modular and scalable architecture, as the API acts as a central point of control and coordination. 

Pros and Cons of API First Approach 

Advantages: 

• Clear and well-defined interface design for effective team collaboration and independent work. 
• Promotes code reusability and facilitates integration with external systems. 
• Improved security measures by incorporating security considerations from the beginning. 
• Enhanced scalability and extensibility, allowing for easy accommodation of future enhancements. 
• Automatic generation of API documentation from the design, reducing documentation efforts and ensuring up-to-date information. 

Here’s a clip from a recent Astera webinar, “Unlock the Power of APIs the Code-Free Way,” in which Mehdi Medjaoui, founder of the famous Apidays Conference, discussed the numerous benefits of adopting the API-first approach in detail: 

Limitations: 

• Requires upfront planning and design effort, potentially slowing down development. 
• Assumes that all design decisions can be made early, which may not always be feasible. 
• Potential delay in implementation due to the need for a finalized API design. 

API Design First: A Subset of API First Approach 

API-design first is a subset of the broader API-first approach that focuses specifically on the design aspect of building APIs. With the API-design first approach, designers create a detailed API specification before coding occurs. This specification serves as a blueprint for developers to ensure the API is created according to the desired functionality and requirements. 

There are a few key principles that form the foundation of the API Design First approach: 

• Designing for the Consumer: With Design First, the focus is on the needs and expectations of the developers consuming the API. Developers can create a user-friendly and efficient API by considering their requirements from the outset. Developers consider factors such as ease of use, simplicity, and consistency when designing for the consumer.  
• API Contracts: An API contract defines the rules and specifications that govern the interaction between the API and its consumers. Designing the API contract first allows for better collaboration between API providers and consumers, ensuring that both parties are on the same page regarding functionality and expectations.  
• Documentation as a Priority: Good documentation is critical to the success of any API. By prioritizing documentation from the design phase, developers can ensure that the API’s consumers can access clear, accurate, and up-to-date documentation, reducing the learning curve and facilitating integration. 

Comparing API-First and Code-First Development Methodologies 

The table below highlights the core differences between the two approaches: 

Aspect	API First	Code First
Design Philosophy	Design-driven approach, with the API carefully planned and designed before implementation.	Implementation-driven approach, where the design evolves alongside the code.
Development Process	Iterative development of the API as the foundation, enabling parallel work by multiple teams.	Sequential development where code is written first and API is refined afterward. May require synchronization efforts.
Flexibility and Control	High level of control with upfront planning, clear boundaries, and standardized interfaces.	Prioritizes speed and agility, allowing rapid adaptation but may result in inconsistencies and lack of standardized interfaces.
Integration	Easier integration with external systems and third-party applications due to well-defined APIs.	Integration may be more challenging if APIs are tightly coupled with the codebase.
Scalability and Extensibility	Scalability and extensibility are considered from the beginning, leading to a more robust and maintainable codebase.	May face challenges in maintaining and extending the codebase as the design evolves with the code.
Development Efficiency	Promotes parallel development, reducing dependencies and bottlenecks, resulting in faster feature delivery.	May lead to longer development cycles and potential bottlenecks when multiple teams are involved.

Criteria For Selecting the Best Approach 

When deciding between both approaches, there are several key considerations to keep in mind: 

• Project requirements: Businesses should consider the specific needs and goals of the project. Is the project focused on immediate functionality or long-term scalability? 
• Team expertise: Organizations need to evaluate the skills and experience of their development team. Are they familiar with API design principles or have more experience with traditional code-first development? 
• Time constraints: Assess the project timeline and available resources. Does the project have enough time for upfront API design, or is there a need for quick implementation? 

Making the Right Choice: API First or Code First? 

Choosing between API First and Code First in software development depends on the project’s requirements and constraints. API First is suitable for well-defined projects, scalability, and integration with external systems. It provides structure, security, and ease of integration when the team has API expertise. It’s also good for scalability planning. 

Code First is ideal for projects with evolving or ambiguous requirements, emphasizing flexibility and agility. It’s useful for rapid prototyping, quick iterations, and adapting to changing requirements. It’s best when the team is strong in coding and prefers working directly with the codebase, allowing for faster feedback and leveraging existing tools. 

Ultimately, the choice depends on project specifics, team expertise, and desired outcomes. Careful evaluation is essential for a successful development process. 

Astera offers a user-friendly, no-code API design solution that enables you to create and utilize APIs easily, simplifying the API implementation and maintenance process. Incorporating the Astera API design and implementation tool into your API strategy can strengthen your capacity to respond to changing business requirements, streamline your data workflows, and guarantee a smooth user experience. 

Contact us to learn more about how Astera can help you.