How to Build an API: A Comprehensive Guide on API Development

Are you struggling to understand how to build an API from scratch? This guide will equip you with everything you need to know about API development. APIs are the backbone of modern software, enabling applications to communicate, share data, and integrate seamlessly. From social media platforms to e-commerce websites, APIs are everywhere.

So whether you’re considering building an API to expand your offerings, connect existing systems, or streamline operations, this resource will provide the insights you need. We’ll break down the technical jargon, explore how APIs can benefit your business, and outline what to expect during the development process. Let’s get started.

What is API and how does it work?

An Application Programming Interface (API) is like a digital bridge that allows different software applications to communicate and share data. APIs define a set of rules and protocols that specify how requests and responses are exchanged between systems. 

APIs typically work through requests and responses. A client (like your app) sends a request to a server (like a database or external service), and the server responds with the necessary information, all in real-time.

What is an Example of an API?

Think of a weather app. It relies on APIs to fetch up-to-date weather data from a remote server and display it on your device. You see only the forecast, but behind the scenes, APIs handle all the complex data exchanges.

How Difficult is API Development?

API development can range from straightforward to complex, depending on your business needs. Building a simple API for internal use might be quick, while a robust, secure, and scalable API for external users requires expertise.

At GoodCore, we specialise in custom API development that meets your unique business requirements. Whether you need to streamline operations or connect with third-party services, our experienced team ensures a seamless, secure, and efficient API solution tailored to your goals. 

How to Build an API?

Building a successful API isn’t just about code. It’s a process that requires careful planning, thorough testing, and ongoing support — at least, that’s what our team considers non-negotiable. So, here’s how to build an API from scratch in several steps:

Planning and Design

Before writing a single line of code, you need to have a plan. At GoodCore, we closely collaborate with you to learn your business goals, target audience, and the API’s intended use. We’ll work with you to:

• Define API scope and functionality
• Choose a suitable API type
• Design a user-friendly API architecture

Development

With a solid plan in place, we translate that vision into code. Our API software development covers implementing the necessary functionality, security measures, and access controls — all with scalability and performance in place.

Testing

Just like any software, APIs need rigorous testing before deployment. GoodCore uses the following testing methodologies to ensure your solution is secure, reliable, and performs well:

• Unit and functional testing. We check all API endpoints to make sure they work as intended.
• Integration testing. We test how your API interacts with other systems and applications.
• Security testing. We handle security tests to find and solve any vulnerabilities in your API.

Deployment

Once we test your API, it’s time for deployment. As part of this process, we handle:

• Deployment environment selection. We choose the most suitable deployment environment based on your needs, whether cloud-based hosting or on-premises infrastructure.
• Actual deployment. Our team deploys your API to the chosen environment.
• API documentation. We create crystal-clear documentation with described API calls, use cases, error codes, and code snippets, so you can understand your API in depth.

Maintenance and Support

Even after deployment, we keep improving your API. Here’s what we typically do at this point:

• Bug fixes and security updates
• Performance monitoring
• API versioning and updates

What are the 4 main types of APIs?

While we covered the API basics above, let’s explore further. Here are the most common types of APIs, each suitable for specific needs and use cases:

REST APIs

REST (or RESTful) APIs are a popular and widely adopted architectural style. They leverage standard HTTP methods (GET, POST, PUT, DELETE) for data manipulation and retrieval. Known for their simplicity, scalability, and reliability, REST APIs are perfect for web services and mobile apps.

Typical use cases include:

• Web apps
• Mobile apps
• Integrations
• Internet of Things
• Financial services
• Cloud services
• Content management systems

Key features:

• Stateless. Each request-response interaction is independent, meaning the server doesn’t store information about previous requests.
• Layered. You can structure REST APIs with multiple layers, each with its own functionality or service.
• Resource-oriented. APIs focus on accessing and manipulating resources identified by URLs.

What is Rest API Example?

An example of a REST API is a weather application fetching data from a weather service. When a user searches for the weather in a specific city, the app sends a GET request to the weather service’s REST API, which responds with the current weather data for that city, displaying it on the app.

SOAP APIs

SOAP (Simple Object Access Protocol) APIs use a strict, XML-based protocol for communication. This makes them best for enterprise-level applications where security and reliability are a must.

Typical use cases include:

• B2B integrations
• Financial services
• Telecom
• Web services
• Legacy systems

Key features:

• Structured data exchange. SOAP uses XML messages to define data formatting, transmission, and processing.
• Enterprise-focused. SOAP’s structured nature makes it well-suited for complex data exchange often seen in enterprise applications.
• Platform-independent. You can use SOAP APIs to enable communication between apps on different OSs and programming languages.

GraphQL APIs

GraphQL is a data query language for API development. Here’s what makes it special. Unlike REST APIs, which select predefined data structures, GraphQL allows users to specify the exact data they need and receive it in a single request. This makes GraphQL APIs more flexible in terms of data manipulation.

Typical use cases include:

• Complex user interfaces
• Mobile applications
• Single-page applications
• Third-party integrations

Key features:

• Query language. Developers select and get the required data in one request, without making multiple calls.
• Flexible data retrieval. A single request can retrieve data from multiple resources within the API.
• Improved developer experience. The GraphQL queries’ clear structure and flexibility simplify development and maintenance for complex data interactions.

WebSocket APIs

WebSocket APIs differ from the previous API types as they set up a persistent, two-way communication channel between the client and server. Hence, they allow for real-time data exchange, perfect for apps that need constant updates — think live chats or online games.

Typical use cases include:

• Streaming services
• Internet of Things
• Collaborative editing tools
• Real-time analytics tools
• Chat applications
• Online games

Key features:

• Bidirectional communication. Data can flow in both directions simultaneously between the client and server, enabling real-time interaction.
• Lower overhead. Compared to traditional HTTP APIs, WebSocket offers a more efficient way to handle real-time data updates.
• Persistent connection. The connection between the client and server remains open, which enables continuous, real-time data exchange.

Want to learn more about different types of APIs? Check out our latest post on third-party API integration in healthcare apps.

API Development Tools

Learning how to build an API platform requires more than just exploring the main development stages. You also need the right tools to handle the job. Here’s the selection of those that our team frequently uses:

API Design Tools

The tools you can use to design your API include:

• Swagger is a complete API editor that lets you design, document, and test your API.
• Postman is a tool for designing, building, and testing APIs. It also allows you to create documentation and collaborate on your APIs.
• Insomnia, another popular API design tool, offers features for designing, mocking, and testing APIs.

Development Frameworks

Once you complete the design, you can start developing APIs using the following frameworks:

• Django. This Python-based high-level framework lets you build secure and scalable APIs.
• Express.js. Based on JavaScript, this framework is best for developing lightweight and efficient APIs.
• Flask. One more popular Python framework, Flask, offers a minimalist approach to API development, allowing engineers to focus on essential features.

Testing Tools

You can test the developed API using the following tools:

• JUnit. This tool is suitable for unit testing of your API.
• Pytest. A versatile testing framework, Pytest lets you test Python-based APIs.
• Newman. This command-line collection runner is used to test APIs designed by Postman.

Monitoring and Analytics Tools

After deployment, you should keep monitoring your API’s performance. Here are several tools for this:

• New Relic. This platform allows you to monitor your entire stack, from logs and security to system health.
• Splunk. This tool, best for enterprises, offers AI-powered solutions for observability and security.
• Datadog. Similar to New Relic, this platform provides detailed insights into your API performance.

Must-Have Features of an Efficient API

Here are the must-have features every API should include:

• Ease of Use: A well-designed API should have intuitive endpoints and detailed documentation. This reduces the learning curve and speeds up integration.
• Scalability: An API must handle growing traffic and data loads without compromising performance, ensuring it supports business growth seamlessly.
• Security: Robust security measures like authentication, encryption, and rate-limiting safeguard sensitive data and prevent unauthorised access or abuse.
• Consistency: Uniform response formats and naming conventions create a predictable experience, making it easier to use the API effectively.
• High Performance: APIs should respond quickly, with minimal latency, to ensure applications depending on them deliver a smooth user experience.
• Versioning: Supporting multiple API versions ensures backward compatibility, allowing updates without disrupting existing integrations.
• Monitoring: Real-time analytics and logging enable tracking of API usage, performance, and potential issues, ensuring optimal operation over time.

GoodCore’s Best Practices in API Development

At GoodCore, we follow industry-best practices to ensure our APIs are robust, secure, and user-friendly. Here are some of the key approaches we adopt:

Throttling

We implement throttling to limit the number of API requests a user can make within a specific timeframe. This prevents misuse, protects server resources, and ensures consistent performance for all users.

Overriding HTTP Method

When working with systems that don’t support all HTTP methods (e.g., DELETE or PUT), we use method overriding techniques. This ensures compatibility while preserving the intended functionality of the API.

SDK and Libraries

To simplify integration, we provide Software Development Kits (SDKs) and libraries in popular programming languages. This enables developers to implement APIs more quickly and with fewer errors.

Security

We prioritise security with measures like authentication, encryption, and token-based access. This ensures data protection and prevents unauthorised use of the API.

Documentation

GoodCore delivers comprehensive API documentation, including endpoint details, request/response formats, and example code. This empowers you to use the API effectively with minimal friction.

Why should you develop an API?

The reasons you may want to jump into custom API development or integrate existing APIs with your app include the following:

• Improved connectivity. APIs bind different apps and services together and set standards for data formats, creating a more cohesive ecosystem.
• Enhanced functionality. APIs let you pack your app with cutting-edge features without reinventing the wheel. You can leverage existing (and time-tested!) solutions like social media, weather services, or navigation systems to enrich your application’s capabilities.
• Better integration between systems. APIs connect disparate apps seamlessly, even when dealing with different operating systems, programming languages, or hardware infrastructures.
• Improved scalability and performance. Well-designed APIs can handle increased traffic and provide you with the means to scale as necessary.
• Increased product value. Handling API development and integration allows you to offer more value to your users. You can implement the features your audience begs for, significantly outperforming your competitors.

But there’s always a ‘but.’ To achieve the above advantages from APIs, you should build them with a well-thought-out plan in mind. Luckily, GoodCore can help you out. Choose our API development services to get robust and reliable solutions tailored to your goals.

How much does it cost to build an API?

The cost of building an API can vary widely based on its complexity, functionality, and the level of customisation required. Here’s a rough estimate to give you an idea:

• Simple APIs: For internal use with basic features like CRUD operations (Create, Read, Update, Delete), the cost can range from $5,000 to $10,000.
• Moderate APIs: APIs with additional security, scalability, and integration with third-party services may cost between $10,000 and $20,000.
• Advanced APIs: Public-facing APIs with advanced features such as real-time analytics, robust authentication, and SDKs for multiple platforms can range from $20,000 to $50,000 or more, depending on the project scope.

These costs include planning, design, development, testing, deployment, and initial support. Factors like ongoing maintenance, hosting, and updates should also be considered. Partnering with a professional development team like GoodCore ensures transparency in costs and a high-quality API tailored to your business needs.

Common Challenges in API Development and How to Overcome Them

API development comes with its own challenges, but with the right strategies and expertise, they can be managed easily. Here are some common obstacles you may face and how GoodCore tackles them:

Security Issues

According to the State of API Security Report 2024, 95% of companies experienced some kind of security issues in their APIs. Typical problems include injection attempts, unauthorised access, and man-in-the-middle attacks. To address these, we use input validation techniques, multi-factor authentication, and secure communication protocols.

Performance Bottlenecks

APIs with inefficient code are slow and frustrating. The same applies to those solutions that cannot scale properly and handle unexpected traffic spikes. Luckily, we design with scalability in mind, ensuring your API delivers a fast and responsive user experience, even under heavy loads.

Integration Difficulties

When integrating an API with your other systems, you may face difficulties due to incompatible data formats and limited technical resources. We tackle this by transforming data into a unified format and providing you with detailed API documentation.

Documentation and Usability

Finally, you may find it hard to use an API if its documentation is filled with technical jargon, lacks code samples, or is outdated. Our team delivers only well-documented APIs and constantly updates the knowledge base whenever changes are made.

How GoodCore can help with API Development?

For almost 20 years in the market, GoodCore has been consistently delivering reliable APIs and software to clients. Our success wouldn’t be possible without following our steadfast principles:

• Security is a priority
• Clients are at the centre of our work
• Scalability is a must

Besides, we emphasise expertise and constant growth. Our team is well-versed in REST, SOAP, GraphQL, and WebSocket APIs and provides solutions for various industries, with healthcare, education, and SaaS being just a few. Our offerings include:

• Enterprise system integration
• Data integration
• Third-party API integration
• Custom API development services

Learn more about what we can do for you by viewing our recent API development case study.

GoodCore’s API Development Success Story

Our healthcare client, CoolCare4, needed an API that would bring together all their data from various sources in a single place. We had to connect information from multiple care homes, including details about the homes themselves, their staff, and the residents.

To handle all of this, we wrote complex SQL queries tailored specifically to what our client needed. Security was another concern, so we included solid authentication and authorisation mechanisms. 

As a result, the API we built allows for easy information retrieval and updates across all these databases.

Conclusion

API development is the first step in building a hyper-connected world. It allows your app to easily exchange data with other systems and deliver robust features to your users.

Yet, building a successful API requires expertise and a well-thought-out plan. Luckily, GoodCore can help with that. If you want to know how long does it take to build an API or have any other questions left, contact our team for in-depth consultation. Let’s discuss how APIs can transform your business together.

FAQs

What are the key stages of API development?

The API development process at GoodCore consists of the following stages:

1. Planning and design
2. Development
3. Testing
4. Deployment
5. Maintenance and support

What are some API development best practices?

The best practices in API development that we apply cover four main areas: security, documentation, versioning, and scalability. That means we focus on robust security measures, develop comprehensive API documentation, create a clear versioning scheme, and design scalable API architectures.

How do different API architectural styles compare, and which should I choose?

The main styles of API architecture are REST APIs, SOAP APIs, GraphQL APIs, and WebSocket APIs. Each solution offers distinct strengths for specific use cases. REST is the best choice for a simple and scalable API. If you need robust security, select SOAP. GraphQL is perfect for complex user interfaces, while WebSocket is a decent option for real-time data exchange.

What should comprehensive API documentation include?

API documentation created by GoodCore includes descriptions of API endpoints and functionalities, code snippets, and error codes, along with clear examples and use cases.

How can I ensure my API remains compatible as it evolves?

To ensure compatibility, the best API development companies leverage versioning systems, establish deprecation policies, and maintain backward compatibility.

How to develop REST API?

To develop a REST API, start by planning its structure, endpoints, and data flow. Use a framework like Express.js, Django, or Flask to write and implement the API, ensuring it adheres to REST principles. Test thoroughly, deploy on a secure server, and provide clear documentation for seamless integration.

How to learn API development?

To learn API development, start with the basics of HTTP, REST principles, and JSON formatting. Explore tutorials and courses on frameworks like Express.js or Django, and practice building simple APIs. Hands-on projects and tools like Postman for testing can help you gain practical experience.

What is API in software development?

In software development, an API (Application Programming Interface) is a set of rules and protocols that allow different software applications to communicate and share data. It defines how requests and responses are exchanged between systems. APIs enable seamless integration of features, such as payment processing or third-party services, into applications.

What is JSON API?

A JSON API is an API that uses JSON (JavaScript Object Notation) as its data format for requests and responses. It simplifies data exchange between clients and servers with a lightweight, human-readable structure. JSON APIs are widely used due to their efficiency and compatibility with various programming languages.