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Charge your APIs Volume 26: Choosing the Right API Development Strategy: A Guide to API Design First vs. Code First Approaches

16.4.2024 | 6 minutes of reading time

In today's digital world, Application Programming Interfaces (APIs) are crucial for creating flexible and scalable software. The way APIs are designed and implemented, particularly through API Design First and Code First approaches, plays a vital role in project success. This blog post compares these methodologies and integrates Team Topologies to guide software development teams. It aims to help developers, managers, and stakeholders choose the best API strategy to align with their organisational goals and achieve superior software solutions.

Understanding API Design First

The API Design First approach emphasises careful planning before coding to create a robust API blueprint, minimising costly revisions later. This method begins by defining the API’s purpose and users through discussions among stakeholders like developers, business analysts, and end-users, aiming to align the API's functions with business and user needs. The design phase uses standards like OpenAPI to set clear specifications on the API's behaviour.

Feedback is crucial once a draft design is developed, allowing stakeholders to highlight discrepancies and make necessary adjustments before coding begins. This collaborative process ensures the final API meets user expectations and reduces the likelihood of future modifications. Further validation may involve sharing the API specifications with potential consumers or related teams to gain additional insights, refine the design, and utilise mocking to simulate API responses for thorough testing.

Key benefits of API Design First include fostering collaboration and early problem detection, making it cheaper and simpler to modify the API design rather than correcting issues during or after development. This strategy ensures the API satisfies consumer needs effectively. However, challenges include the substantial initial investment in design and planning, which may delay the start of actual development and, if overly rigid, could limit flexibility in responding to changing requirements during the project.

Understanding Code First

In the Code First approach to API development, developers dive directly into coding based on initial requirements, focusing on quick start-up and adaptation as the project evolves. Unlike the Design First approach, which emphasises upfront design and documentation, Code First allows the API to develop organically through coding iterations. Documentation and specifications are generated post-development, using tools like Springfox to ensure alignment with the actual implementation.

This approach offers the advantage of rapidly kickstarting projects, especially useful in environments with evolving requirements or tight deadlines. It permits ongoing adaptation, fostering innovation by allowing changes during the development process.

However, Code First has challenges, including the risk of creating APIs that cater to short-term needs but lack long-term usability, potentially making them difficult to integrate or use. This approach also tends to sideline non-developer stakeholders, as the API design emerges from the code, reducing their influence and possibly leading to costly late-stage changes, including the risk of introducing breaking changes that can significantly disrupt existing systems.

Despite these issues, Code First is favoured in many development teams for its speed and flexibility, particularly where user requirements are initially vague or likely to change. Effective management is crucial to ensure that the final API is user-friendly and meets broader business objectives.

Comparing API Design First and Code First

In API development, choosing between the API Design First and Code First approaches greatly influences project outcomes, impacting team collaboration and product quality. Each method's strengths and weaknesses vary by scenario.

The API Design First approach emphasises pre-coding design and structure. It involves early collaboration among stakeholders like developers, business analysts, and end-users to establish API specifications. This approach typically results in a more predictable and stable API that closely aligns with user needs, as it establishes a documentation "contract" that guides development, enhancing consistency and minimising later changes, which can be costly.

Conversely, the Code First approach allows developers to begin coding immediately based on initial requirements, facilitating rapid prototyping and iterations. This method suits dynamic environments where requirements may evolve, offering flexibility to adjust to changes without a pre-established contract. However, this flexibility can lead to issues if the API design does not meet user needs or if significant reworking is needed for integration.

Key considerations in choosing between the approaches include:

  • Time to market: Code First can initially speed up development by skipping extensive design phases. However, potential delays from later changes might offset this advantage.
  • Flexibility and scalability: Code First provides developmental flexibility, while API Design First often results in a more scalable API, as the initial design anticipates growth and user changes.
  • Impact on API consumers: API Design First offers a stable, predictable interface for users, while Code First can lead to faster access but might cause disruptions if changes are needed.

The decision between API Design First and Code First depends on the project's specific needs and context. Clear, stable projects might benefit from API Design First, ensuring a common understanding of the API before coding. Projects in fast-evolving industries might prefer Code First to adapt quickly to new requirements without frequent redesigns.

Ultimately, choosing between these methodologies is about finding the best fit for the project's conditions, team dynamics, and strategic goals, ensuring the approach aligns well with operational realities.

Integrating Team Topologies

Incorporating the Team Topologies framework helps determine whether to use an API Design First or a Code First approach, influenced by team structures and communication styles. Team Topologies categorises teams into four main types—Stream-aligned, Complicated Subsystem, Enabling, and Platform—each with distinct roles and interaction modes: collaboration, X-as-a-Service, and facilitating. These aspects heavily influence API strategy choices.

Stream-aligned teams, which focus on rapid feature delivery from a business perspective, often favour the Code First approach for its quick development cycle, allowing for immediate coding based on requirements. This approach suits their need for agility, though it may compromise long-term scalability and robustness.

Conversely, Platform teams prioritise consistency, reliability, and scalability, making the API Design First approach more suitable. By defining the API structure upfront, Platform teams ensure that all internal consumers have a stable and well-documented interface, preventing the risks associated with unplanned and incompatible APIs developed in isolation.

The interaction modes defined by Team Topologies also guide the appropriate API strategy. For example, a Stream-aligned team may collaborate with an Enabling team to rapidly prototype using Code First, benefiting from swift iterations. In contrast, a Platform team might provide its API as a service, using a well-designed API as a contract to ensure scalability and reliability without frequent inter-team negotiations.

By analysing team types and their expected interactions, organisations can align their API strategy with their operational needs and overarching goals of efficiency, scalability, and maintainability. Choosing between API Design First and Code First transcends technical considerations, reflecting strategic organisational decisions about structure, culture, and objectives.


In our examination of API development methodologies, we've contrasted the structured, stakeholder-involved API Design First approach with the more flexible, rapid-development-oriented Code First approach. API Design First promotes early issue detection and strong alignment with user needs through detailed upfront planning, leading to more robust and user-focused APIs. On the other hand, Code First caters to dynamic environments with evolving requirements, offering speed and adaptability but potentially complicating long-term maintenance and scalability.

The choice between API Design First and Code First extends beyond technical aspects to strategic alignment with team structure and organisational goals. Utilising Team Topologies to understand team interactions and dynamics can guide the selection of an API strategy that enhances productivity and operational efficiency.

The right API strategy should be tailored to the specific needs and capabilities of your organization, aiming to create scalable, adaptable software solutions. Reflect on these approaches, discuss them with your team, and choose the path that best supports your goals in the evolving landscape of software development.


Charge your APIs Volume-24: Harmonizing API strategy and team dynamics

Optimizing Digital Ecosystems: The Synergy of API Federation and Team Topologies

Springfox Reference Documentation

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