What is the API-First approach?

API development approaches refer to the methodologies used for creating APIs, encompassing activities like planning, documentation, implementation, testing, and maintenance. 

The three common approaches are:

• Code-First
• Design-First
• API-First

It's possible to combine or customize these approaches to suit specific project requirements.

Factors like project complexity, team dynamics, upfront planning needs, requirements flexibility, and integration requirements should guide the choice of the API development approach.

💡 Deep Dive: API Development Approaches

✅ Approach #1: Code-First

In the Code-First approach,developers interpret requirements to define API endpoints, schemas, and logic, using tools like OpenAPI to generate specifications, documentation, and artifacts.

Using this approach, the ‘code’ is the single source of truth over the API specification.

Here is an overview of the Code-First approach:

Focus:

• Design the API through coding and generate the associated artifacts later.

Benefits:

• No Design phase to slow down development.
• Dev Team has the freedom to implement changes as project requirements evolve.

The API specification is closely coupled with the API implementation.

Challenges:

• Lack of clarity, effective communication, consistency, and coordination between teams.
• Making changes during development is more costly than during the Design phase.

The following is an overview of Code-First’s key components:

Design through Code

Instead of starting with a formal API specification or design document, developers begin by writing the actual code that implements the API endpoints and the associated logic. 

Then, they define the API’s request/response models, authentication mechanisms, and other aspects of the code.

Frameworks and Annotations

Developers use frameworks and libraries to annotate the code with API details. 

These frameworks can parse the code and generate an API specification. 

Using the specification, they use tools like Swagger to generate API documentation, client SDKs, and artifacts. 

Automation helps ensure consistency and reduce manual effort in maintaining documentation.

Iterative Development

This approach is highly flexible because it allows developers to iterate on an API’s design and make changes quickly, allowing for faster development cycles.

Strong Integration with the Implementation

The tight coupling between the API code and the spec is beneficial in scenarios where the API needs to align closely with implementation requirements and underlying business logic.

✅ Approach #2: Design-First

Design-First is a collaborative approach whereby stakeholders from all walks of the business participate in designing the API using language and tools that ‘make sense to everyone.’ 

Here is an overview of the Code-first approach:

Focus:

• Cross-functional stakeholders design and document the API spec upfront before writing code.
• The API specification acts as a contract during development.

Benefits:

• Clear and consistent team communication through shared understanding of the API spec.
• Front-end and back-end teams can work in parallel.
• Making changes during the design phase is cheaper.

Challenges:

• The upfront design effort and team coordination are resource-intensive.
• Delays in cross-functional communication and layers of bureaucracy can slow things down.

Design-First’s key components includes:

Extensive Design Phase

Stakeholders, including developers, must communicate in a ‘shared language.’

Developers and non-developers collaborate using a shared set of tooling, which usually includes visual API design tools. 

They can then generate Open API specifications in machine-readable formats.

NOTE: The overview of Design-First’s other key components is briefed at original blog.

• Specification as Contract
• Documentation
• Validation and Mocking

✅ Approach #3: API-First

Companies may have a variety of products and services they offer.

However, API-First companies view the API as the most critical product that glues together all other products.

Here is an overview of the API-first approach:

Focus:

• Prioritize API development over other software components
• Create an API ecosystem in which every API plays a specific role

Benefits:

• A consistent developer experience across APIs
• APIs evolve independently with reduced dependencies
• Standards define the interaction of system components

Challenges:

• Requires advocacy to communicate why a business should prioritize APIs
• Lack of parallel development with front-end teams

The following is an overview of API-First’s key components.

Sequence

The API is the primary interface connecting all the separate software, services, or applications you can interact and exchange data with.

As such, API-first businesses build APIs before services, components, and user interfaces that rely on the API.

In contrast, Design-First and Code-First may not prioritize building the API over other components.

For example, teams may wish to create the user interface while making the API.

NOTE: Remaining API-First’s key component topics mentioned below is briefed at original blog.

• Modularity and Reusability
• Interoperability
• Developer Experience (DX)

💡 A Hybrid Approach: API-First and Design-First

Combining API-First with Design-First allows you to have the best of both worlds.

You can prioritize the development of your API while also taking advantage of the collaboration using a common language and shared tooling.

This hybrid approach has several benefits contributing to its efficiency, flexibility, and scalability. 

The following are some key advantages.

Design Clarity and Consistency

When you prioritize the API over other software components, you can focus on designing the API so it is maximally useful.

Teams can create a well-defined contract outlining the endpoints, data structures, and expected behavior.

This clarity ensures consistency across different components and enables effective communication between teams.

Scalability and Agility

A well-designed API provides a scalable architecture.

It allows for adding or replacing back-end services without affecting the front-end implementation.

This flexibility enables agile development practices, making it easier to adapt and evolve the application over time.

NOTE: Remaining advantages of hybrid approach is briefed at the original blog.

• Innovation and Collaboration
• Versioning and Maintenance

📈 Challenges of API-First/Design-First

Using a combination of API-First and Design-First presents some challenges that teams need to consider. 

The most common challenges are as follows.

Upfront Design

Creating a well-defined API specification requires more upfront design work.

This can be resource-intensive and requires careful planning and collaboration between teams that sometimes have different priorities.

API Changes

Changing the API as requirements evolve offers flexibility but can lead to complex and costly changes.

In addition, a challenge when iterating is maintaining backward compatibility with existing clients.

How do you follow an API-First / Design-First approach?

To successfully follow this hybrid approach, you must ensure your company prioritizes APIs over other products and that teams commit to a collaborative effort to build the API.

Taking an API-First and Design-First approach to API development involves following steps and practices prioritizing the design, documentation, and iteration of the specification and implementation code in parallel.

A general guideline for adopting this hybrid approach is as follows.

Identify Requirements

Before writing the specification, ensure teams understand the requirements for the API by identifying its essential functionalities, data structures, and interactions that the API needs to support.

Define API Contract

Choose an API architecture and specification language that aligns with those requirements.

Next, specify the data models, operations, and authentication mechanisms, then use the appropriate tools to create and generate an API specification like OpenAPI, RAML, or API Blueprint.

NOTE: The remaining guidelines mentioned below is briefed at the original blog.

• Collaborate
• Validate
• Mock and Prototype
• Implement
• Test
• Document and Generate SDKs
• Deploy and Version
• Iterate

The following is an overview of API-First’s key components.

Sequence

The API is the primary interface connecting all the separate software, services, or applications you can interact and exchange data with.

As such, API-first businesses build APIs before services, components, and user interfaces that rely on the API.

In contrast, Design-First and Code-First may not prioritize building the API over other components.

For example, teams may wish to create the user interface while making the API.

A Hybrid Approach: API-First and Design-First

Combining API-First with Design-First allows you to have the best of both worlds.

You can prioritize the development of your API while also taking advantage of the collaboration using a common language and shared tooling.

This hybrid approach has several benefits contributing to its efficiency, flexibility, and scalability. 

The following are some key advantages.

Design Clarity and Consistency

When you prioritize the API over other software components, you can focus on designing the API so it is maximally useful.

Teams can create a well-defined contract outlining the endpoints, data structures, and expected behavior.

This clarity ensures consistency across different components and enables effective communication between teams.

Scalability and Agility

A well-designed API provides a scalable architecture. It allows for adding or replacing back-end services without affecting the front-end implementation.

This flexibility enables agile development practices, making it easier to adapt and evolve the application over time.

NOTE : Remaining advantages of hybrid approach is briefed at the original blog.

Challenges of API-First/Design-First

Using a combination of API-First and Design-First presents some challenges that teams need to consider. 

The most common challenges are as follows.

Upfront Design

Creating a well-defined API specification requires more upfront design work.

This can be resource-intensive and requires careful planning and collaboration between teams that sometimes have different priorities.

API Changes

Changing the API as requirements evolve offers flexibility but can lead to complex and costly changes.

In addition, a challenge when iterating is maintaining backward compatibility with existing clients.

NOTE: The remaining challenges of API-First/Design-First is briefed at the original blog.

• Communication and Collaboration
• Learning Curve
• Testing and Validation
• Governance
• Third-party Dependencies

How do you follow an API-First / Design-First approach?

To successfully follow this hybrid approach, you must ensure your company prioritizes APIs over other products and that teams commit to a collaborative effort to build the API.

Taking an API-First and Design-First approach to API development involves following steps and practices prioritizing the design, documentation, and iteration of the specification and implementation code in parallel.

Check out the full article below 👇 on what is the API-First approach?