What is an API First Approach?

Building fast, flexible, and scalable software is essential for businesses today. The API-first approach meets those needs by reversing the traditional development process. 

Instead of treating APIs as an afterthought, it makes them the foundation of the entire project.

This approach ensures that all the pieces of your tech stack can connect, communicate, and evolve seamlessly from the start. 

Let’s explore why the API-first approach is becoming the go-to method for modern software development. 

What is an API?

Before we explain an API first approach, let's take a step back. 

An API, or Application Programming Interface, is a set of rules that allows software applications to communicate with each other.

Think of an API as a waiter in a restaurant — instead of going to the kitchen yourself, you tell the waiter what you want. The waiter takes your order, gets it from the kitchen, and returns it to you. 

Similarly, an API acts as a messenger between two apps — one app makes a request, the API passes it to another app, and then returns the data or result.

For example, when you check the weather on your phone, the app uses an API to request data from a weather service, providing the displayed information.

Different types of APIs

APIs come in various forms, each with its unique purpose and access level. Here's a quick overview of the most common ones:

Open APIs (Public APIs)

Open APIs are public and can be used by any developer to access specific data or functionality from a service.

ℹ️ Example: The Google Maps API allows you to add maps to your website or app.

Partner APIs

Partner APIs are shared with specific business partners or external developers but not the public. These require permission or a special agreement to access.

ℹ️ Example: A travel booking site might use a partner API to allow airlines or hotels to connect to their system for bookings.

Internal APIs (Private APIs)  

Internal APIs are only available within an organisation. Developers use them to connect different internal systems and services.

ℹ️ Example: A company might use an internal API to connect its HR system to its payroll software.

Composite APIs

Composite APIs combine multiple APIs into one call. This allows developers to access multiple endpoints when multiple data pieces are required.

ℹ️ Example: A shopping app might use a composite API to get product details, pricing, and customer reviews in one request instead of three separate calls.

What is an API-first approach?

An API-first approach means the API is designed first at the beginning of the software development process. 

This differs from the traditional approach, where the application code is written first, and the API is added later. 

Focusing on the API from the beginning ensures that everything, like the user interface and other features, can easily connect and work together.

Why does it matter?

Modern software development is moving away from monolithic architecture and choosing microservices instead. 

Microservices break down software applications into small, self-contained services that work together. 

Think of an e-commerce website: instead of one large program handling everything, there might be separate microservices for product listings, shopping carts, and payment processing.

This allows businesses to build modular systems that fit their specific needs. This makes adding new features or making changes easier without overhauling the entire system. 

💡What is Monolithic Architecture?

Monolithic architecture refers to a traditional way of building software, where all components (like the user interface, database, and backend logic) are bundled together in one large system. This makes updating or scaling specific parts harder without affecting the entire system.

API first strategies are crucial for this setup because they allow the different pieces to communicate with one another. 

In an API-first approach, the API acts like a bridge between all the components, ensuring they work smoothly. 

This makes it easier for businesses to create flexible, scalable tech solutions that meet their unique challenges.

On the other hand, a code-first approach, where APIs are created later in the process, can cause issues. 

The Key Components Of An API First Philosophy

Adopting an API-first philosophy shifts the focus of software development, ensuring that the API is at the core from the beginning of the software development lifecycle. 

Below, we’ll discuss the other fundamental principles of an API first strategy.

Early and frequent testing

In API-first development, testing happens early and often to make sure the API works well and meets both business goals and user needs. 

Testing is built into the development process, using automated tools to regularly check the API’s functionality. This approach often goes hand in hand with Test-Driven Development (TDD), helping ensure the API stays in line with the project’s goals.

💡What is Test-Driven Development (TDD)?

Test-driven development (TDD) is a software development approach in which tests are written before any code. The idea is simple: first, create tests defining what the code should do, then write the actual code to make those tests pass. Here’s how it works in three steps:

1️⃣ Write a test:

Before writing any code, create a test that defines what the function should do. For example, write a test that checks if a function returns the correct total for items in a cart.

2️⃣ Write code to pass the test:

Write just enough code to make the test pass. Your goal is to ensure the functionality works as expected without worrying about perfection yet.

3️⃣ Refactor:

Once the test passes, clean up or improve the code while ensuring the test still passes. This keeps your code efficient and maintainable. 

Understanding business needs is crucial

Successful APIs start with a clear grasp of business requirements.

Early involvement of both technical and non-technical stakeholders ensures the API aligns with business goals and user expectations. 

Gather detailed requirements upfront and consider using tools like product roadmaps and UML diagrams to streamline the process.

APIs must be modular, scalable, and reusable 

API-first development focuses on building consistent and reusable APIs. Here’s what we mean: 

🧩 Modularity: Breaks the API into smaller, manageable parts that can be reused across different projects.

📈 Scalability: Ensures the API can handle increasing traffic and data as your business grows.

🔄 Reusability: Simplifies maintenance and updates by using the same components across multiple applications.

Case study: Orbit

A great example of this approach is one of our secret weapons: Orbit. 

Orbit is a suite of software code modules called “Capsules.” Each capsule performs common functions in most software projects, such as sign-up processes, payment systems, and data security. 

By combining the necessary capsules, developers can assemble the core elements of a new app in minutes, knowing that each part is thoroughly tested, secure, and compatible.

Unlike traditional software development, where everything is built from scratch, Orbit enables developers to build digital products faster and with fewer errors, making API-first development more efficient and reliable.

💡Key Point: API First = Money Saved 

An API-first approach reduces the need to build everything from scratch. This reusability saves time and money, enabling teams to quickly build a basic version of the product (minimum viable product) and then integrate additional features using APIs connected to pre-built components.

Provide clear API documentation

Comprehensive API documentation is essential. It should cover how to use the API, its features, limitations, data formats, and error handling. Also, be sure to include information on authentication and authorisation.

We recommend that your documentation always be up-to-date and easily accessible. Create a central place where everything related to your APIs is stored: API specifications, documentation, contracts, etc.

Use HTTP verbs appropriately

When defining API operations, use the correct HTTP verbs to match the type of action being performed. 

HTTP verbs tell the API what kind of operation you want to perform. There are several standard HTTP verbs, each used for a specific type of action:

• GET: Used to retrieve data from the server. 
• POST: Used to create new data on the server.
• PUT: Used to update existing data. 
• DELETE: Used to remove data from the server.

By using HTTP verbs correctly, your API becomes RESTful (a widely used standard for APIs) and easier to understand for developers. 

It becomes more intuitive because the type of action (like retrieving, updating, or deleting data) is clear based on the verb used.

Use consistent data models

In API-first development, ensure your APIs use a consistent data model. This means organising and formatting data uniformly across APIs. 

For example, if one API represents user data with firstName, lastName, and email, all other APIs handling user information should adhere to this structure.

This consistency allows an API program to communicate easily and with other systems. It reduces the need for extra work to reformat data, saving time and minimising errors during development and integration.

💡Pro-tip: Establish a Company-Wide API Style Guide

Develop a comprehensive API style guide to foster consistency and reusability across teams. Standardise crucial elements like API status codes, error handling, and versioning.

Collaboration is essential

API-first development thrives on early and continuous collaboration. 

Involving everyone — development teams, analysts, product owners, and users — ensures the API meets both business goals and user needs, minimising the need for major revision across the entire API lifecycle.

Implement strong authentication and authorisation

Both external and internal users will use APIs, so security is a top priority. Strong authentication (verifying who someone is) and authorisation (what they can do) are essential.

To control access, use API keys (unique identifiers for authorised users) or OAuth (a standard for secure authorisation). This protects sensitive data and ensures that only authorised users can interact with the API.

Benefits of an API-First Approach

Highlights problems early on

API first design emphasises thorough planning before coding. This upfront focus helps identify potential issues early on, like mismatches between front-end needs and backend capabilities, reducing unexpected problems later in development.

Better developer experience 

Since APIs are the foundation of an application in API-first development, they often come with thorough documentation and tools that make them easier to use. 

This approach also encourages creating reusable components, which can be tested and debugged separately.

Developers can work more efficiently, reducing the learning curve and making building on top of the API easier. This leads to better productivity and a smoother development process.

Interoperability

When you use an API-first strategy, your app makes its data and functions available to developers, allowing different parts of your tech stack — like your content management system (CMS), digital asset management (DAM) system, and others — to communicate seamlessly.

This means you can easily create workflows connecting different tools and services without writing much extra code. 

It’s worth noting that this depends on whether you use open APIs (for external access) or closed APIs (for internal use only); you can tailor the level of accessibility based on your business needs.

Less susceptible to faults

Systems built using microservices connected through APIs can be more fault-tolerant and better handle failures. 

Distributing incoming requests across multiple instances (load balancing) and building backups (redundancy) allows the system to run even if one part fails. 

For example, if one microservice goes down, the rest of the system can work smoothly.

Language and platform flexibility

APIs provide a common way for different parts of the system to communicate, regardless of what programming languages or platform they’re built on. 

This makes it easier for your software systems to work with various services, even if written in different languages or technologies.

More scalable systems

APIs help create loosely connected systems, meaning that the different parts of the system (like services) don't depend too much on each other. 

REST APIs keep these connections simple and "stateless," meaning they don’t need to remember previous interactions. 

This setup makes it easier to scale (grow) the system, as you can easily add or remove parts of the system, like microservices, depending on how much traffic or demand you have at any given time.

Key Considerations When Using An API First Development Approach

Below we’ll discuss a few considerations to keep in mind when implementing an API first strategy. 

Design complexity

Designing an API that works well for the business and its end-users can be challenging. It requires a deep understanding of the business needs, system architecture, and user expectations. 

Striking the right balance between flexibility, functionality, and simplicity can be difficult, making the design process time-consuming and intricate.

Integration complexity

Integrating the API with existing systems and services is another potential hurdle. The API needs to work smoothly with various systems, which can be hard to achieve. 

Security, compliance, or performance issues may arise during integration, requiring extra attention and adding complexity to the process.

Testing complexity

Testing APIs is often more involved than testing other system components. APIs must be tested independently and in conjunction with other parts of the system. 

This requires a thorough understanding of the API’s design and functionality, making the testing process time-intensive and often requiring specialised skills.

API governance and management

Strong governance is essential to ensure APIs are used consistently across an organisation. 

This can be particularly challenging in larger companies with multiple teams and developers, as maintaining consistent API design, usage, and security across all departments requires careful management and oversight.

Final Thoughts

The API-first approach is revolutionising how we build software, making it faster and more adaptable to businesses' ever-changing needs. 

By prioritising APIs from the outset, you can create a robust foundation for your tech stack that promotes seamless communication, scalability, and a superior developer experience.

While there are challenges, like design complexity and integration headaches, the benefits far outweigh the hurdles. If you're ready to embrace the future of software development and unlock the full potential of your applications, the API-first approach is the way forward.

🚀 Ready to take your software development to the next level? Rocketmakers is here to help you design, develop, and deploy API-first solutions that drive innovation and propel your business forward. Contact us today to explore how we can transform your ideas into reality.