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Exploring SOAP API: Advantages and Implementation Strategies

Discover the benefits and best practices of SOAP APIs and learn how SOAP can enhance your business functions.

If you use various tools to run your business, you may have heard of APIs. APIs are code that allows two programs to communicate with one another. For instance, if you use accounting software with an inventory management system, the integrations use APIs to effectively pass data to one another.

Another example of an API in use is integrations with other software. For example, marketers often integrate customer relationship management (CRM) software with their social media platforms to give them advanced analytics and reports.

There are two types of APIs: SOAP and REST APIs. In this article, we’ll focus on SOAP APIs to help you understand how they work and how to use them in your business. So what is SOAP API? Keep reading to find out.

What is SOAP API?

SOAP — Simple Object Access Protocol — is an API that uses Extensible Markup Language (XML) data to send requests and responses. SOAP APIs communicate using Hypertext Transfer Protocol (HTTP) and allow applications and various types of software to communicate with each other.

SOAP messages are built in XML, which establishes a set of structural rules for messages. When sending messages from web applications to other applications, SOAP sends the messages and requests in XML code only.

History of SOAP

SOAP was developed in 1998 for Microsoft when interactions between various software were custom coded or built with middleware that enabled them to pass data. Many companies in the software industry realized how time-consuming and expensive this process was, so they designed a set of standards for integration and data exchange.

SOAP and other web service standards were the basis for new frameworks that enabled various types of software on different networks to communicate and share information. As a result, this API protocol became the standard, allowing businesses to shift data between various networks and applications.

How SOAP API works

SOAP allows you to receive responses from a variety of XML document platforms. XML documents include coding consisting of the following tags:

  • Message: The message is the information shared between two applications. When one application sends a request to another, the second software authenticates the first with an API key to grant it access to information. For example, when your analytics dashboard pulls data from Google Analytics, the software must ensure that there’s a Google Analytics API key that allows them to communicate.
  • Header: The header element provides additional information for the message being sent.
  • Envelope: The SOAP envelope is the core element of a message and includes the XML document message.
  • Body: The body of the soap message includes the request or response from one program to another.
  • Fault: The fault tag displays data about errors throughout the process.

You can think of SOAP APIs as the digital mailman that ensures one platform’s message makes it to another.


When considering integrating various applications, you have several options, including SOAP vs. REST APIs. Some of the differences between SOAP and REST APIs are the message format, data encoding, protocol, security measures, language, and architectural style

The most significant difference between SOAP and REST API is that SOAP is a protocol while REST — Representational State Transfer — is more of a style. When one client-server requests information using a REST API, the server sends a response to the current information.

REST APIs follow a request and response process; when these APIs receive requests for data, they return the request with all the relevant information they have in an easily digestible format. SOAP also utilizes the XML format to transmit data, whereas REST is an architectural style that employs HTTP to transfer data in diverse formats.

Another difference between the two APIs is the programming language that is used. SOAP uses Web Services Description language to explain the functionalities of web services, while REST API uses Web Application Description language.

As we’ve mentioned, SOAP is a strict protocol, and its primary goal is to prevent unauthorized access to the information in the message. On the other hand, REST is considered less secure than SOAP APIs because they don’t have a built-in security system, and instead, the security of one API depends on how it was built.

RESTs are typically better for building public APIs because they’re more flexible. Conversely, SOAP APIs are better for private APIs for larger enterprises because the data transferred is decentralized and secure.

Additionally, you might use SOAP when using a transport protocol other than HTTP since SOAP is independent of the transport protocol. Instead, you might use Simple Mail Transfer Protocol (SMTP), which is used for sending emails between servers and clients like Apple Mail.

Benefits of using SOAP API

As we’ve mentioned, SOAP is less flexible than REST because it has a strict set of XML rules it must adhere to. While SOAP APIs are commonly used for developing private APIs for internal business functions, they can also be used for public APIs.

Some of the benefits of using SOAP API include:

Enhanced security

SOAP APIs are incredibly secure because they authenticate and authorize API calls to ensure information is passed only to the correct software or users. These APIs can use any underlying transport protocol, but the most common is HTTP, allowing them to use other authentication processes on top of its existing security features.

Simply put, SOAP prevents unauthorized users from gaining access to important data. To do this, it uses Web Standards (WS) Security that regulates the authentication procedures, including passwords, encryption, tokens, and other advanced security features.

Of course, there are several public SOAP APIs that don’t require this level of authentication. However, if you want to keep your business finances safe, SOAP API may be better suited for you than REST API.

More reliable transactions

SOAP is more secure than REST because it uses encryption to protect the transfer of data, making it more reliable. In addition, the built-in security features of SOAP APIs prevent message corruption or unauthorized access.

For instance, accounting software, banking websites, and other platforms that store your financial information may use SOAP APIs as account security best practices to protect customer information.


Because SOAP APIs adhere to strict XML standards, they’re standardized with an HTTP protocol that makes it easier to operate across systems. Additionally, SOAP has a strong emphasis on standards, which some may see as a disadvantage because it’s less flexible than REST.

Less coding

SOAP can be less complex than REST, requiring less coding for more security. However, this isn’t always the case. SOAP typically has a higher learning curve than REST and is harder to code because you must adhere to strict XML standards.

Language independence

SOAP is compatible with all programming languages, allowing software to exchange data and developers for creating applications that access data from a variety of sources regardless of the underlying programming language.

Disadvantages of SOAP API

While you can use SOAP for public or private APIs, it's best suited for private enterprise applications. This is because SOAP has several drawbacks for public APIs, such as:

  • Bandwidth requirement: XML documents are large and require more bandwidth, making it slow to process tags.
  • Difficult to learn: Since it’s a protocol, SOAP API servers require an understanding of all the protocols you might use and possible restrictions.
  • No flexibility: SOAP is much more strict than REST and requires additional work to ensure messages are accurate. Therefore, updating requests and responses can be tedious and time-consuming.

How to use SOAP APIs

SOAP can be a useful API for various solutions, especially when you need your applications to communicate in a structured format. Additionally, some types of APIs require SOAP because they’re the default protocol for a specific application.

As we’ve mentioned, APIs allow two software applications to communicate. APIs occur behind the scenes when you integrate one software application with another. A few real-world SOAP API examples include the following:

  • Data and analytics: You worked hard on your website design and want to ensure it’s performing while supporting your other marketing initiatives. One way to measure the effectiveness of your marketing campaigns and compare them to sales and overall company goals is to integrate analytics with a single dashboard. Since SOAP APIs are considered more secure, you might use them to transfer information from one application to an analytics dashboard that’s used for internal data-driven decisions.
  • Bank transfers: SOAP APIs are beneficial when they must perform repetitive tasks. Online bank transfers are another instance when you might use SOAP instead of REST to protect the privacy and security of someone’s financial data.
  • Websites: APIs are now commonplace on websites. When you build a website, you want it to be easy to use and offer a good user experience. For example, you might see a SOAP API in use during the checkout process when shopping online. Website security is crucial for all e-commerce companies, but when you add payment options, you need an even more secure integration to protect your customers’ financial information.

The future of SOAP API in web services

Many companies already use APIs to enable their applications to work with other types of software and provide their customers with a good user experience. However, some enterprises have complex internal processes that existing public APIs can’t support, so they might turn to SOAP APIs, which are more secure and structured.

APIs are crucial for any business, and understanding how they work can help you decide which integrations can help you reach your goals.

Mailchimp uses APIs to integrate with thousands of other software applications and platforms to help you manage your marketing strategy from one dashboard. Try Mailchimp today and learn how SOAP APIs can improve your web services.

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