What Is the Difference Between REST and SOAP APIs?
As you start learning about APIs, you quickly discover that there is more than one way for systems to communicate. Two of the most common styles are SOAP and REST, and both have been widely used for years. To understand the difference between REST and SOAP, it helps to start with what an API is in general.
An API is simply a way for one program to talk to another. You send a request, the system performs work, and you receive a response. The design, format, and structure of these requests can vary depending on the type of API. REST and SOAP are two different approaches for how that communication should happen.
SOAP, which stands for Simple Object Access Protocol, is the older of the two. SOAP APIs follow a strict, rules-heavy approach to communication. Messages are sent using XML, and both the request and the response follow a very detailed structure. SOAP also relies heavily on something called a WSDL file, which is a document that describes how the API works and what operations are available. Because of the strict format, SOAP often feels more formal and heavier. It was designed for large enterprise systems where reliability, security, and clearly defined contracts were critical. Financial systems, banking applications, and large corporations often embraced SOAP because the strict rules reduced the chance of communication failures between systems.
REST, or Representational State Transfer, takes a much simpler approach. Instead of using a special protocol, REST works with standard web technologies. A RESTful API uses regular HTTP calls like GET, POST, PUT, and DELETE, the same methods your web browser uses every day. Instead of focusing on operations, REST treats information as resources. Each resource has its own address on the web. For example, a REST API for users might provide a URL such as:
https://api.example.com/users/10
A GET request to that URL might return user number 10. A DELETE request to the same URL might remove that user. REST is flexible with the data formats it returns, though JSON has become the most popular because it is easy to read and works naturally with modern programming languages.
To see the difference more clearly, imagine a simple example where your application needs to look up today’s weather. A SOAP request might require building an XML document that follows a specific structure, wrapping your question inside predefined tags, sending it to the server, and then parsing a detailed XML response. Nothing in this communication is especially difficult, but it requires more overhead and more ceremony.
A REST request for the same information might be a simple URL such as:
https://api.weather.com/today?city=Seattle
You could paste that into your browser and see the result instantly. The server might respond with a short JSON message giving you the temperature and weather conditions. The whole experience is lighter, faster, and easier to understand at a glance.
Both approaches have their strengths. SOAP focuses on strong reliability, built-in error handling, and standardized contracts that protect communication between systems. It is well suited for large internal business systems where everything must be precise and controlled. REST is more flexible, simpler to learn, and fits naturally with the web as we know it today. It is widely used in modern web and mobile applications, especially where fast development and easy integration are important.
SOAP and REST are not different kinds of APIs so much as different styles of designing an API. SOAP uses a formal structure with strict rules and XML-based messaging. REST uses standard web methods and treats data like resources that can be accessed through URLs. Both get the job done, but REST is usually easier for beginners to learn and is now the most common choice for modern application development.
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