REST APIs have become the backbone of modern software applications, enabling seamless communication between systems and ensuring data consistency. In particular, REST APIs are useful for ETL (extract, transform, load) and data integration workflows. They make it easy to exchange information between various websites, databases, and SaaS (software as a service) applications. Whether you're building a mobile app, a web application, or integrating third-party services, understanding how to create a robust REST API is crucial.

Here are the 5 key takeaways from the article:

  • An API (application programming interface) allows two software systems to communicate. REST (representational state transfer) is a popular architectural style for building web services, with 83% of APIs using REST over older protocols like SOAP.
  • RESTful APIs adhere to six principles: Uniform interface, Client-server architecture, Statelessness, Cacheability, Layered system, and optionally, Code on demand. These principles ensure consistency, scalability, and efficiency in API interactions.
  • REST APIs play a pivotal role in ETL and data integration processes. They offer efficiency in data transfer, real-time integration, scalability, and platform-agnostic communication, making them ideal for data-driven operations.
  • The process involves planning and identifying resources, designing intuitive URIs, choosing data formats (like JSON), setting up the development environment, defining and implementing CRUD operations, ensuring security, testing, and proper documentation.
  • There are various frameworks and tools, such as Python Flask, Node.js, Ruby on Rails, and Spring, that simplify the REST API creation process. Adhering to best practices, like proper endpoint naming, ensuring data security, and graceful error handling, is crucial for building robust and efficient APIs.

In this article, we will guide you through the process, from understanding the importance of REST APIs in data integration to the nitty-gritty of designing and implementing one.

Table of Contents

What is a REST API?

In computing, an API (application programming interface) is a collection of functions and protocols that enables two software applications or systems to communicate with each other. The API defines a common set of commands, as well as the appropriate way to invoke these commands. 

As such, an API adds a layer of abstraction on top of the “messy” technical details of the API implementation. By adding an abstraction layer, APIs make development less complex and help to clean up the codebase while software components become more reusable and modular.

One good analogy for an API is the menu at a restaurant. The menu represents the possible interactions that you can have with the restaurant (i.e., the types of dishes that you can order). You don’t need to know what’s going on in the kitchen behind the scenes to receive and enjoy your meal. Similarly, when using an API, you don’t need to know the specifics of how the system retrieves the data you want from behind the API — you only care about the answer you get back.

So, what is a REST API? REST (representational state transfer) is a software architectural style commonly used for building web services such as APIs. According to a 2017 study, 83 percent of APIs now use the REST architecture, while 15 percent use the older SOAP protocol.

REST comprises six principles (five mandatory and one optional). An API that complies with these principles qualifies as a RESTful API:

  • Uniform interface: All clients should be able to interact with the REST API in the same manner, whether the client is a browser, a mobile app, or something else. The REST API is usually accessible at a single URL (uniform resource locator) — for example, “”
  • Client-server architecture: In REST APIs, the client and server are two separate entities. Concerns about the API interface are separate from concerns about how the underlying data is stored and retrieved.
  • Statelessness: REST requests must be stateless; the server does not have to remember any details about the client’s state. This means that the client must include all necessary information within each API request it makes.
  • Cacheability: REST servers can cache data by designating it as cacheable with the Cache-Control HTTP header. The cached result is ready for reuse when there is an equivalent request later on.
  • Layered system: The REST client does not know (and does not need to know) if it is communicating with an intermediary layer in the architecture, or with the server itself.
  • Code on demand (optional): The client can optionally download code such as a JavaScript script or Java applet in order to extend its functionality at runtime.

Why Use REST APIs in ETL and Data Integration?

REST APIs make data integration and ETL processes more efficient and secure, allowing for easier data transfer between services. Their features such as cacheability, layered systems, and optional code on demand make them an ideal solution for many data-driven operations. Let's explore how these features can be used to streamline ETL processes:

  • Efficiency in Data Transfer: REST APIs provide a standardized way to exchange data between different systems, ensuring that ETL processes can extract, transform, and load data seamlessly.
  • Real-time Integration: REST APIs enable real-time data integration, ensuring timely insights and actions as data updates in one system are immediately reflected in another.
  • Scalability: As data volumes grow, REST APIs can handle the increased load without significant changes to the existing infrastructure.
  • Flexibility and Interoperability: Being platform-agnostic, REST APIs ensure smooth communication between diverse systems, from legacy platforms to modern cloud applications.

How to Make a REST API

Creating a REST API is more than just writing code. It's about understanding the needs of the users, ensuring data security, and designing a system that's both robust and scalable. Whether you're a seasoned developer or just starting out, the following guidelines and best practices will help you in your journey to create an effective REST API.

Planning and Designing a REST API:

  1. Identify the Resources – Object Modeling:

    • Begin by pinpointing the core entities or resources for your API. These are the primary objects you'll be dealing with. For instance, in a healthcare system, resources might encompass Patients, Doctors, and Appointments.
  2. Create Model URIs:

    • Design intuitive URIs for each resource. Examples include:
      • /patients for all patients.
      • /patients/{id} for a specific patient.
      • /doctors/{id}/patients for all patients associated with a specific doctor.
  3. Determine Resource Representations:

    • Decide on the data format for your resources. While both XML and JSON are popular, JSON has become the standard for many modern APIs due to its simplicity and compatibility with JavaScript.

Going into Depth on Creating a REST API:

  1. Planning:

    • Before diving into code, map out the resources your API will provide. For instance, in a bookstore API, resources might encompass Books, Authors, and Orders.
  2. Setting Up the Development Environment:

    • Opt for an environment tailored to your chosen tech stack. For instance, if you're using Node.js, consider Express.js as a framework and Postman for testing.
  3. Defining Endpoints:

    • For each resource, define the CRUD operations. For a Books resource, you might have:
      • POST /books to add a new book.
      • GET /books to fetch all books.
      • GET /books/:id to retrieve a specific book.
      • PUT /books/:id to update a book's details.
      • DELETE /books/:id to remove a book.
  4. Implementing CRUD Operations:

    • Develop the backend logic for each endpoint, ensuring robust error handling.
  5. Setting Up Authentication and Authorization:

    • Implement security measures, such as JWT, to ensure that only authorized users can access certain parts of your API.
  6. Testing:

    • Before deployment, rigorously test each endpoint. Consider using automated testing tools for efficiency.
  7. Documentation:

    • Properly document your API using tools like Swagger, ensuring it's accessible and understandable for other developers.

Frameworks and Tools for Building REST APIs:

While there are numerous ways to build a REST API, leveraging existing frameworks and tools can expedite the process:

  • Python Flask: A web framework in Python, with the Flask-RESTful extension allowing quick REST API development.
  • Node.js: The restify framework is used by giants like Netflix and Pinterest for scalable REST APIs.
  • Ruby on Rails: Starting from Rails 5, it includes an “API mode” for streamlined web API creation.
  • Spring: Java's Spring framework offers an in-depth tutorial for crafting REST APIs.

Given the plethora of platforms and tools, there's seldom a need to build a REST API from scratch. However, the approach to "how to make a REST API" largely depends on the implementation and programming language.

Evergreen Best Practices:

JSON vs. XML: Both are standards for data exchange in REST APIs. XML is typically chosen for metadata and document markup, while JSON, being less verbose, is preferred for most other scenarios.

Name Your Endpoints Appropriately: Adhere to conventions like:

Consider Data Security: Given the sensitive nature of data exchanged, prioritize data security. Use protocols like SSL/TLS for encryption and enforce strict access control.

Fail Gracefully: Incorporate error handling in your REST API. Common HTTP error status codes include:

  • 400 Bad Request (a client request error, such as bad syntax or an invalid message framing)
  • 401 Unauthorized (the client has not been authenticated)
  • 403 Forbidden (the client is authenticated but not authorized to access the resource)
  • 404 Not Found (the requested resource is not found)
  • 502 Bad Gateway (the server received an invalid response from another server)
  • 503 Service Unavailable (the server is overloaded or under maintenance)

In conclusion, creating a robust and efficient REST API requires a blend of understanding foundational principles, meticulous planning, and leveraging the right tools. Whether you're a novice or a seasoned developer, adhering to best practices and continuously updating your knowledge will ensure your APIs are top-notch.

How Can Help with REST APIs


As mentioned above, REST APIs are helpful for extracting your data from one or more sources and moving it to a centralized repository, often a data warehouse or data lake. But how can you streamline the REST API creation process for data integration? can help. The platform is a powerful, feature-rich ETL and data integration tool with a simple drag-and-drop interface and more than 100 pre-built connectors — including a REST API connector.

Related Reading:’s REST API Connector

The REST API connector is ideal when you’re trying to retrieve data from a third-party website or service, such as YouTube or Instagram. You can also make REST APIs that fetch data from internal systems but do not fully expose the database layer.

Ready to start building REST APIs for your enterprise data with Then contact our team of data experts to discuss your business needs and to start your 14-day pilot of the platform.