SOAP vs REST API: Key Differences, Examples, Pros and Cons

Introduction

SOAP and REST are two common ways applications exchange data through APIs, but they work differently.

SOAP is a strict protocol that uses XML and is commonly used in enterprise, banking, payment, and legacy systems.

REST is an architectural style that commonly uses HTTP and JSON, making it lighter and easier to use for web apps, mobile apps, SaaS platforms, and public APIs.

SOAP vs REST: Quick Answer

What is an API?

An API, or Application Programming Interface, allows two software systems to communicate with each other.

For example, an accounting platform can use an API to send invoice data to an ERP, CRM, payment gateway, or reporting dashboard.

How APIs Work: Simple Example

Think of an API as a messenger between two systems. When one application requests data, the API receives the request, sends it to the right system, and returns the response.

For example, when a SaaS product requests customer invoice data from an accounting system, the API defines how that request should be sent and how the response should come back.

SOAP and REST handle this process differently.

What is SOAP API?

SOAP, or Simple Object Access Protocol, is a protocol used for exchanging structured information between applications.

It uses XML as its message format and follows strict rules for request and response communication.

A SOAP message usually includes an envelope, header, body, and fault structure.

This makes SOAP more formal and heavier than REST, but also useful for systems that need strict contracts, reliability, and advanced security.

What is REST API?

REST, or Representational State Transfer, is an architectural style used to design lightweight APIs. REST APIs usually communicate over HTTP and use common HTTP methods like GET, POST, PUT, PATCH, and DELETE.

REST commonly uses JSON because it is lightweight and easy to read, but it can also support XML, HTML, plain text, and other formats.

REST APIs are stateless, meaning each request is handled independently without relying on previous requests.

REST is widely used for web applications, mobile apps, SaaS products, public APIs, and microservices.

REST APIs are commonly used in modern ERP and finance platforms where applications need to create, update, retrieve, or delete records such as customers, vendors, items, invoices, and sales orders.

For a practical example, check our Dynamics 365 Business Central integration guide.

What is the Difference Between SOAP vs REST APIs?

SOAP vs REST API: Key Differences

1. Protocol vs Architectural Style

2. XML vs JSON and Other Formats

SOAP only uses XML for request and response messages. REST commonly uses JSON, but it can also support XML, HTML, plain text, and other formats.

3. Performance

4. Security

5. Use Cases

How SOAP and REST Are Similar

SOAP and REST are different approaches, but both are used to allow applications to exchange data. Both can be used to build APIs, both can communicate over HTTP, and both can support secure communication using SSL/TLS.

The main goal of both approaches is the same: helping software systems communicate. The difference is in how they structure requests, responses, security, and data formats.

Here are other similarities between SOAP and REST:

• They both outline guidelines and expectations for how applications should create, handle, and respond to requests for data from other applications.
• They both communicate using HTTP, a widely used internet protocol.
• Both of them support SSL/TLS for safe and secure communication.
• To create secure, scalable, and fault-tolerant distributed systems, you can utilize either SOAP or REST.

SOAP vs. REST Example

1. SOAP Example:

Using the SOAP API, build up the XML request with the body.

The request body contains an envelope, which is a type of SOAP wrapper that identifies your API request.

The SOAP request body has parameters.

In this case, we want to fetch the student with the name “John”. So based on the below screenshot, our request is built and sent to the API.

Also Read: Create SOAP Web Service with WSDL in ASP.NET Core”

SOAP Message Structure:

SOAP API Request Example

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
  <soapenv:Header/>
  <soapenv:Body>
    <GetStudentDetails>
      <Name>John</Name>
    </GetStudentDetails>
  </soapenv:Body>
</soapenv:Envelope>

The API then provides information on “John” the student, in the form of an XML body response.

SOAP API Response Example

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
  <soapenv:Body>
    <StudentDetails>
      <Name>John</Name>
      <Age>30</Age>
      <Address>California</Address>
    </StudentDetails>
  </soapenv:Body>
</soapenv:Envelope>

2. REST API Request and Response Example

HTTP URLs are used to gain access to the REST API.

The URL must contain parameters if it is to be processed as a GET request.

REST API Request Example

GET https://example.com/students?name=John

The JSON data format is used by the REST API to return Student Details related to the name “John”

REST API Response Example

{
  "name": "John",
  "age": 30,
  "address": "California"
}

Explanation

In the SOAP example, the request is wrapped inside an XML envelope. In the REST example, the request is sent through a simple URL, and the response is returned in JSON format.

This is why REST is often easier for modern developers, while SOAP is preferred where a strict message structure is required.

NetSuite is a good real-world example where businesses may compare SOAP and REST options before choosing the right integration method.

Another Example of Rest is here,

In this example, the client is a web application. REST APIs can be consumed by a broad range of clients, like

• Web Browsers
• Mobile applications
• Desktop applications
• IOTs, i.e., the Internet Of Things

HTTP verbs play a very important role in the Restful Web API.

The most common HTTP verbs are GET, PUT, POST, and DELETE, which correspond to CRUD (Create, Read, Update, and Delete) operations, respectively.

• GET
• POST
• PUT
• PATCH
• DELETE

Here we have displayed the HTTP verb’s operation mode in the visual image.

Further Read: Combine ASP.NET Identity Web API and MVC Best in a Single Web App

When Should You Use SOAP API?

Use SOAP API when your application needs strict standards, enterprise-level reliability, and advanced security.

SOAP is useful when the integration involves sensitive data, complex transactions, or legacy systems that already use SOAP-based services.

Use SOAP when:

• You are working with banking, payment, insurance, healthcare, or telecom systems.
• The system requires WS-Security.
• The integration needs strict XML-based message contracts.
• You need ACID-style transaction reliability.
• You are connecting with a legacy ERP or enterprise application.

When Should You Use REST API?

REST is a better fit for modern web apps, mobile apps, SaaS platforms, public APIs, and microservices.

Use REST when:

• You are building a SaaS product or public API.
• You need lightweight JSON-based communication.
• You want easier integration with web and mobile apps.
• You need better scalability.
• You want to use standard HTTP methods like GET, POST, PUT, PATCH, and DELETE.

SOAP vs REST for Accounting, ERP, and SaaS Integrations

For accounting, ERP, and SaaS integrations, the choice between SOAP and REST depends on the systems being connected.

Many modern SaaS platforms and accounting tools prefer REST because it is lightweight, easier to work with, and supports faster API communication.

However, some legacy ERP, banking, payment, and enterprise systems still rely on SOAP because of strict contracts, XML messaging, and advanced security needs.

In real business integrations, the right answer is not always SOAP or REST. Many companies need both, depending on their accounting system, ERP, payment gateway, and reporting requirements.

SOAP vs REST: Pros and Cons

SOAP vs REST API Comparison Table

SOAP vs REST: Which One Should You Choose?

For many businesses, especially those working with accounting, ERP, CRM, eCommerce, and payment platforms, the best approach may involve both SOAP and REST.

The right choice depends on your system architecture, security needs, data format, integration complexity, and long-term maintenance plan.

Also, both SOAP and REST can be used to create custom API Integration services that allow different applications to communicate and share data effectively.

The choice between SOAP vs REST depends on factors like the specific requirements of the integration, the existing technology stack, and the desired level of flexibility and complexity.

Should you require any further refinements or clarifications, please do not hesitate to contact us.

FAQs

What is the main difference between SOAP and REST API?

The main difference between SOAP and REST API is that SOAP is a protocol with strict XML-based messaging rules, while REST is an architectural style that commonly uses HTTP and JSON. SOAP is more structured and often used for enterprise systems, while REST is lighter and widely used for web, mobile, and SaaS applications.

Is REST faster than SOAP?

Yes, REST is usually faster than SOAP because it commonly uses lightweight data formats like JSON and supports HTTP caching. SOAP uses XML, which can make request and response messages heavier and slower to process compared to REST.

Is SOAP more secure than REST?

SOAP supports WS-Security, which makes it useful for enterprise, banking, payment, and other high-security systems. REST can also be secure when implemented with HTTPS, OAuth, JWT, API keys, and strong authentication practices.

When should you use SOAP API?

You should use SOAP API when your integration needs strict standards, XML-based messaging, advanced security, transaction reliability, or compatibility with legacy enterprise systems. SOAP is commonly used in banking, insurance, telecom, healthcare, payment processing, and older ERP systems.

When should you use REST API?

You should use REST API when you need a lightweight, flexible, and easier-to-scale API for web apps, mobile apps, SaaS platforms, public APIs, and microservices. REST is a better choice when speed, JSON-based data exchange, and easier development are important.

Can SOAP and REST APIs be used together?

Yes, SOAP and REST APIs can be used together in the same application or integration environment. Many businesses use REST for modern SaaS, CRM, and mobile applications while still using SOAP to connect with legacy ERP, banking, finance, or enterprise systems.

Which is better for accounting and ERP integrations: SOAP or REST?

REST is often better for modern accounting and SaaS platforms because it is lightweight and easier to work with. SOAP may be better for older ERP, banking, payment, and enterprise systems that require strict contracts, XML messaging, and advanced security standards.

Does REST replace SOAP?

No, REST does not fully replace SOAP. REST is more common in modern API development, but SOAP is still used in enterprise, financial, healthcare, payment, and legacy system integrations where strict standards and reliable transactions are important.