REST vs SOAP: What’s the Difference between REST API and SOAP API?

In this article, we have discussed difference between REST API and SOAP API. Comparing REST vs SOAP API, REST works with plain text, JSON, XML and HTML whereas SOAP work only with XML formats. Moreover, SOAP API needs more bandwidth for its usage whereas REST API doesn’t need much bandwidth.

What is an API?

API is a short form used for an application programming interface. API is an interface that establishes connections between multiple software programs or a mixture of hardware-software mediators. You can read here complete guide of API development.

You must admit that all machines have their different languages to operate. We need web services to establish intercommunication between the machine and the exchange data. Several regulations were made to set the restrictions in the communication that we call web services. These services help define the type and the format of data. We need to exchange that data and the contract between machines with intercommunication.

However, this communication system has two types. Either we can use SOAP (Simple Object Access Protocol) or REST (Representational State Transfer). Moreover, these don’t mean the same. So, in this API development guide, we will discuss the difference between these two. Before going further, let’s first define SOAP API and REST API.

Difference between REST API and SOAP API

Web API is relative to both sides of communication, client and browser. Let us discuss two of the most popular APIs.


SOAP is the first API protocol designed to ease the entrance to programs built on different platforms or programming languages. So, we can quickly extract the data from them. The SOAP API has the following advantages.

  • It helps to create automation with use of specific products with certain languages.
  • Specifically designed to detect and handle errors.
  • It is independent of platform, language, and transport.
  • It provides extensibility to ease changes.


REST came into practice after SOAP. The idea to develop REST was to ease the working with different components like Media Components, Objects, and Files. So, it deals with particular hardware devices and accesses the Components. If you define the web services with REST API, it becomes a REST full web service. Here are some advantages of REST API.

  • It is quite compatible with web technologies.
  • REST processes quicker than SOAP.
  • There are no complicated and large learning curves.
  • The solution provided by REST is powerful and efficient.

How to Describe SOAP API?

The following is a format of SOAP Message. The developers construct this message from four blocks. So, we will discuss each blocks. You need only SOAP Envelope and SOAP Body. However, each one is essential to understand their role. So, let us discuss them.

  1. SOAP Envelope:-SOAP API uses XML. But it is not similar to XML documents. SOAP Envelope makes it easy to identify the XML as SOAP.
  2. SOAP Header:- The header in SOAP is optional. Still, it helps to make SOAP extension possible through SOAP modules.
  3. SOAP Body:- The SOAP body contains a large message. It also lets you use namespaces to describe the data. Say, for example, procedures, parameters, and other data.
  4. SOAP Fault:-This tag helps to show error message if the call is not able to finish. So, clients can see the error message. However, fault Tag may include several elements to talk about errors. It includes code, reason, role, node, and detail.

How to Describe REST API?

REST API development has some principles. You can use them to understand how REST works. So, let us discuss them.

  1. Interface Is Uniform:- Rest API provides some constraints with uniform interface. So, developers can identify the resources, manipulate it through representation, getting self-descriptive message, and accessing the hypermedia.
  2. Client-Server:-It is a design pattern to enforce the separation of concerns. So, it can separate the client from database. Thus, it simplifies the components and improves the scalability.
  3. Statelessness:-It ensures that clients have all information required. So, server can process the request from client side.
  4. Cacheable:-It is a constraint that needs the response itself be a cacheable or non-cacheable.
  5. Layered System:- This system lets the client have a constraint on component behaviour. So, no component is visible beyond the layers.
  6. Code-On-Demand:- It is optional. Still, it lets to extend the client functionality through downloading and applying the codes.

When to use REST API and SOAP API

REST API or SOAP API, you can use both. But you should know when to use REST and when to use SOAP. It is quite confusing when you can use REST or SOAP. Therefore, there are some factors you can consider to understand when to prefer which API. So, let us quickly go through the application process.

Use REST Web Services

Simple Object Access Protocol has large and heavier messaging content. So, it needs great bandwidth. Hence, it means you can use REST if there is a constraint for bandwidth.

When you don’t have to manage the state of information for one request to another, you can use REST. The reason is SOAP is more suitable for information flow. Say, for example, e-commerce websites need their customers to add items to a cart. After that, it transfers the items to the payment page. Here, the state is essential.

The developers must use REST if needed to cache lots of requests. It lets users use the same resources multiple times.

REST services simplify the coding. So, it makes the implementation of data quicker than SOAP. Hence, when there is a short time, REST is the best solution.

Use SOAP Web Services

When reliability and security are a priority, SOAP is the best solution. It encourages the synchronization of processes and innovative solutions.

If there is an agreement between the client and the server for the exchange format, SOAP provides the best solution. Say, for example, there is a web service having payment gateways. So, it should only accept the cart items’ names and consider the prices per quantity.

If you require maintaining the request from one to another, the SOAP solution is the best option.

What Are The Key Differences Between SOAP API and REST API?

First of all, let’s believe, all technologies have their unique pros and cons. So, we cannot judge any technique and tool by limited information.

Therefore, we will go in-depth on technical stuff related to SOAP and REST APIs. So, you can understand the technical difference between these web services.

Let us use some technical aspects to compare SOAP and REST APIs. These will make the difference between SOAP and REST clear. Also, it provides some extent of technical information that developers must know.


  • There is no official or standard implementation technique for the REST API because it uses an architectural style.
  • However, SOAP API is itself a protocol. So, it comes with a standard and official implementation.


  • You can integrate the REST APIs with many standards like XML, HTTP, JSON, and URL to transfer the data through communication.
  • Whereas SOAP APIs are solely dependent only on HTTPS and XML files.

The Need of Source

  • Because REST API is flexible for many standards, there is not much need for the resources like SOAP API. So, it becomes easy to use it.
  • Like we have already discussed, SOAP API needs Extra Bandwidth. Additionally, it also requires more resources. The reason is that SOAP needs to convert the data in XML. Of course, it makes the file heavier and significant in size.


  • The developers can use Web App Description Language for REST. So, they can define the core functionalities provided by the web services.
  • SOAP APIs Web Services Description Language. So, it becomes somewhat easier for developers to work with it.

Security System

  • You can use SSL and HTTPS security systems for REST API. So, the data can have some extent of security.
  • SOAP API comes with SSL security and WS-security. So, some of the web services like bank accounts, passwords, banking card numbers, and more provide security.


  • Rest is eligible to use Simple Object Access Protocol API as an underlying protocol for web services. Of course, the reason is that it is only an architectural styled pattern.
  • However, it is not possible with SOAP. SOAP API cannot use REST API. The reason is that SOAP API itself is a protocol, and the REST API is an architectural pattern.

Challenges with Implementing the API

Do you know that Application Programming Interface comes with both clients and servers? The browser offers API for the client, and the web services provide API to clients from the server-side. So, the server uses REST or SOAP API.

However, anything that developers build comes with different challenges. So, developing an API also has some challenges. Let us discuss them one by one.

Challenges with Simple Object Access Protocol API

The following are challenges with SOAP API.

  • The APIs have WSDL Files. It is the document telling clients about operations performed by the web services. It contains information like data to use for SOAP messages and operations through web services. Say, for example, if you require to change WSDL Files based on the business, the clients may require to change their codes too! So, maintaining and updating WSDL Files is critical.
  • SOAP messages are large. So, there is a requirement for large bandwidth to transfer these data to clients.

Challenges with Representational State Transfer API

  • If you consider REST, it cannot provide tight security like SOAP. So, you can only use REST for publicly available URLs. So, it makes the worst system to transfer confidential data.
  • REST does not guarantee a powerful state. So, the application becomes heavier and difficult to maintain for many clients.

Wrapping Up

We have discussed everything about these two REST ans SOAP API. You have now understand the difference between these two and how developing an API goes. If you think your projects and web applications need API development, you can consider API developing company. So, you can integrate your projects with strong web services. If you still have any queries, you can write to us. So, we can help you with that. Also, you can check leading Mobile App development company for APIs development.

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