Join us at 2024 API And Application Security Summit in Columbus!
Join us at 2024 API And Application Security Summit in Columbus!
Join us at 2024 API And Application Security Summit in Columbus!
Join us at 2024 API And Application Security Summit in Columbus!
Join us at 2024 API And Application Security Summit in Columbus!
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API Security

Differences SOAP Vs REST API

REST and SOAP are two of the oldest and most popular application protocols in use today, and are used in a huge chunk of public APIs. It is important to understand the differences between REST and SOAP, what the pros and cons are, and how each can benefit your organization’s goals. In this post, we’ll dig into what REST and SOAP are, how they work, and some of the associated security issues which should be addressed.

Differences SOAP Vs REST API

What is SOAP API ?

Let’s begin with knowing the fundamentals of SOAP. SOAP means Simple Object Access Protocol and is an API development protocol designed with a motive to bring stability and consistency in the data exchange process, which happened between programs built using different programming languages, tools, and platforms. 

It presents a globally recognized set of rules and regulations that anyone willing to achieve seamless client and server interaction needs to follow. Requests in SOAP are delivered using envelopes. These envelopes hold information crucial for request processing. Mostly, the key parts of the SOAP envelope are a header and body attributes. 

Basic Features of SOAP 

Here are some of the key features of SOAP that make it stand out:

  • It is built with XML and can only be used for web services. 
  • SOAP uses a lot of bandwidth for message processing as SOAP messages hold a huge chunk of data. 
  • SOAP can’t be used by REST 

When To Use SOAP?

As SOAP plays a key role in API development, here are the areas where its implementation will be proved fruitful.

  1. Use it for synchronous processing and invocation subsequently 

If the client needs to have certain application reliability and enhance API security then the latest SOAP standard, SOAP 1.2, is here to here. It offers a couple of professional features for seamless and synchronous processing.  

It also supports subsequent invocation of certain APIs and incorporates needed security practices. 

  1. Use it as an official communication 

In situations when server and client are already ready to exchange data in a format then use SOAP 1.2 as it offers a wide range of rigid specifications for such a communication. 

  1. Use it for seamless processing of stateful operations 

For an application that has an obligation to maintain the state from one request to another, using SOAP 1.2 will make the job quick and easy as it endows the developers with a recognized WS* structure for such tasks. 


Example SOAP API 

<?xml version="1.0"?>
<m:Trans xmlns:m=""
  <m:GetEmployee xmlns:m="">

Pros and Cons of SOAP 

Now that the basics of SOAP are clear, it’s time to learn about the merits and demerits that a developer will enjoy with SOAP. 


  • With SOAP, developers will be able to use WSDL. WSDL is the Web Services Description Language used widely to explain web service procedures and access methods. It serves as a comprehensive resource to learn about API consumption. It makes API development a seamless experience. 
  • SOAP is a great tool to have when working with multiple extensions is the aim. It has an amazing compatibility extension like WS Addressing, WS Security, and WS Federation and can join hands with them to double-up the application capabilities. In short, it makes creating highly functional apps a little strenuous task. 
  • SOAP is a protocol-neutral protocol and can be accessed easily via HTTP, SMTP, TCP, and many other kinds of application protocols. This also means a wide range of users can bring it into practice.  


  • While SOAP is doing a wonderful job, it lacks at certain fronts. And, before you think of using it, knowing the areas wherein can disappoint you is crucial. 
  • The biggest drawback of SOAP is that it uses XML for payload data transfer. XML takes longer than usual time for this job that further gives birth to multiple performance issues. 
  • The second thing that can force people to stay away from SOAP is its complicated syntax. It can only work with XML and it demands a little more effort and time to extract or read data from envelopes. So, it lengthens the API development time.  

What is REST API ? 

REST or Representational State Transfer is an undividedly different approach. It’s a type of architectural pattern employed widely for the modern web-based application development task. It administers the key application components like files, even objects, and media components.  

APIs, produced using REST, is ready to present website or application functionality over the HTTP and are supportive with HTTP verbs like getting and POST 

As REST APIs have unmatched interoperability on the web, they have become the prime choice of many. 

REST protocol

Basic features of REST  

  • REST takes the help of Uniform Service locators to reach at the heart of the hardware device components. 
  • REST is the base for data communication, which happened in the modern application infrastructure.
  • While SOAP can’t use REST, REST can use SOAP. It uses it as a key protocol of web services describing the tool. In fact, it will need SOAP for completing the application development as it’s only an architectural pattern and doesn’t have any standard format for explaining web services.  

When to use REST?

If one wants to utilize the full potential of REST, using it in the right place is the key. Here are the key areas wherein it can do wonders. 

  1. Use it when you have restricted bandwidth 

As specified above, SOAP messages utilize a lot of bandwidth. So, if there is a crisis of resources and bandwidth then REST is a life savior. It works wonderfully even if network bandwidth is restrained. 

  1. Use it when there is no need to maintain a state

Operations that involve no adherence with the statelessness in transferring information from one request to another can be done with full accuracy with REST. 

  1. Use it when catching a lot of requests is the need of the hour

Caching of requests is a key operation and needs to be accomplished with full accuracy. With REST, it’s easy to catch the information as it supports it by all means. In fact, it has handled catching information of the same request multiple times. By doing so, it cuts down the time invested in application development. 

  1. Use it when easy coding is required

The coding of REST APIs and services is far more seamless than SOAP. If there is a time crunch and a quick yet effective web application service is required then REST is the right choice to make.  

Example REST API

An example REST API object is shown here:

"name": "XYZ",
"location": "India",
"title": “developer”,
joinYear: 2010

A REST API call is much simpler to explain, as it uses an HTTP request. As we are to fetch a customer’s details here, a GET call will be used. The parameter, i.e. customer’s name will be passed through URI. Let us share the REST version for the above example itself:


As we told you previously, a REST call returns the output data in the JSON format only. So, the output will be easy-to-understand too. In this case, the output is:

{ "name": "Michael", "level": “Premium”, "address": "Toronto" }

Pros and Cons of REST


  • REST came into being a little later than SOAP. Yet, it has managed to garner a notable significance all because of the impressive benefits it renders to the end-users. Here are the perks that every REST user will enjoy.
  • REST is a stateless pattern and allows each web service call to carry all the necessary information. It doesn’t bank upon any other client-server context for information storing. Because of this, it speeds up the entire process. 
  • APIs developed using REST are highly flexible and can collect the server data in multiple formats. Formats like Atom, JSON, and XML are well supported with REST. So, great freedom in using the format is granted. 
  • In REST, responses are catchable. Such responses are great to improve the web service performance as all the unwanted calls to the backend are removed. 


  • No matter how lucrative REST seems, it has some downsides as well. For instance, there are no specific and globally recognized standards, which is the case with SOAP. Because of this, developers end up using it as per their choices and API development becomes complex. 
  • There are a couple of REST permutations. 
  • REST-based applications are also very cramped to the HTTP protocol which restricts them.  

SOAP and REST Examples

After figuring out the essential details about SOAP and REST, it is a good idea to have a practical overview of both. Going through their examples can help you with this. So, read through these examples where the scenario is: Requesting a Customer’s data from the server. The customer’s name is Michael.

  1. Example Usage - SOAP example

While sending a SOAP request, you will have to prepare an XML request carefully, and as per the pre-specified format. To wrap this request in order to get the request identified and considered, you must add a SOAP wrapper. The request parameters needs to be formatted like this:

The format of the SOAP call’s response is almost the same as the input itself. However, its body contains all the details you’d asked for.

<soapenv:Envelope xmlns:soapenv="">


<ns2:CustDetailsResponse xmlns:ns2="">

  1. Example Usage - REST

A REST API call is much simpler to explain, as it uses an HTTP request. As we are to fetch a customer’s details here, a GET call will be used. The parameter, i.e. customer’s name will be passed through URI. Let us share the REST version for the above example itself:


As we told you previously, a REST call returns the output data in the JSON format only. So, the output will be easy-to-understand too. In this case, the output is:

{ "name": "Michael", "level": “Premium”, "address": "Toronto" }

REST API Security Vulnerabilities

  • Injection Attacks

Most common and quite dangerous among others, these intrusions involve insertion of malicious code to a protected API or application. If ignored, it could have severe outcomes, including illicit grant to threat actors into the main system/app, inserting invalid input to the RESTAPIs, and various other threats. Its common-most variants are XSS and SQLi.

APIs that are not backed with best authentication practices like OAuth and API keys are prone to this API cyber risk. It refers to bypassing the methods of identity/authority verification and taking admin-like control over APIs in question.

When at rest and in use APIs are not properly encrypted, they become the victim of this attack. The lack of military-grade encryption opens the door to opportunities for threat actors and they steal/manipulate/misuse sensitive information like bank details, personal details, etc.

When adequate access control measures aren’t implemented correctly, APIs are easy to break down. Depending upon the intent and purposes of the hacker, threats like unauthorized access to multiple accounts, unverified exchange of data/info, and many more hassles are created.

  • HTTP and Lack of TLS

APIs, lacking TLS and HTTP quality standards, is nothing but an open invitation to hackers. The lack of TLS encryption creates an ideal situation for an MITM attack.

MiTM or Man-in-the-middle, whatever you call it; this safety vulnerability allows a threat actor to be a part of secured and sensitive communication happening through the APIs and misuse it.

  • Parameter Tampering

With an intent to alter crucial parameters like price and permission for personal gains, this attack involves modifying the information being exchanged through the compromised channel.

Protect Your REST APIs

SOAP API Security Vulnerabilities

A very common cybersecurity threat for the APIs, DoS stands for Denial of Service and refers to bombarding numerous API calls to make a specific API unavailable for use.

Often referred to as SOAP injection, XXE is the scenario wherein insecure user input is transferred to server-side SOAP messages and XML documents. Using the XML metacharacters, attackers can alter the pre-created XML and conduct such an illicit activity.

It is what an attacker uses to modify the application-generated database queries and make them work as per his will. When performed at SOAP API, it refers to introducing corrupted SQL queries to the API calls.

  • XAML Injections

It implicates the insertion of malicious codes in the XAML, a mark-up language.

This attack takes place when a vulnerable user-side input is transferred to the SOAP API. When it happens, attackers have the full control over the comprised API with anything that they want.

  • SOAP Action Spoofing

SOAP Action Spoofing or MiTM attack concerns introducing an attacker in the middle of the server-client connection for eavesdropping, data stealing, or other purposes.

  • Broken Access & Authorization

Caused due to the absence of acceptable access/authorization validation criteria, this type of API security threat can lead to hassles like modified URLs, JSON Web Token tempering, and many more.

XSS implies communication compromise by an API. The 2 communicating entities here are the server and vulnerable API.

Why is REST Faster Than SOAP Web Services?

As quoted above, SOAP uses a complex and standard format. There is no shortcut. Everything has to follow certain rules and regulations. XML is already very tedious. Hence, it is time-consuming. 

REST, on the other hand, uses a simple route, JSON, and even cuts down the communication time by caching the information. So, it reaches its target at a much faster pace. 

protocol layering

SOAP vs. REST API: Which is More Secure? 

API security is one aspect that would be the priority, regardless of what approach you chose. While REST is faster than SOAP and makes things easier, we have to admit that SOAP is more secure.  

Both SOAP and REST can use SSL or Secured Socket Layer for protecting the data during the API call request. However, SOAP goes an extra mile and supports Web Services Security as well. Using this extension, application developers can double-up the API security and keep tons of hassles at bay. So, SOAP is better than REST when API security is a matter of concern.  


Benefits of REST Over SOAP 

  1. REST grants a wide range of data formats to work with. SOAP is very limited at this front. Other than XML, it doesn’t support anything else. 
  2. REST, when used with JSON, is a piece of cake. Without much complexity, it can be used.  
  3. Brower clients, using REST, are going to enjoy great technical support.  
  4. As caching of information, done is REST, is not altered, and is dynamic, the applications will have better performance. 
  5. It’s most commonly used and has been praised by leaders like Amazon, eBay, Google, and Yahoo for its seamless operations. 
  6. REST is easy to work with at every front. Whether you talk about its ability to work with less bandwidth or amazing integration power, it stands out at every front. Developers will be able to work from scratch and finish the job in less time. However, that speediness will have no negative impact on the functionality. It will still be top-notch. 

Benefits of SOAP Over REST 

  1. SOAP offers a pre-made retry logic that is used as compensation for failed communication. REST has no such thing. In case of communication failure, retrying is the only option. 
  2. SOAP is a highly standardized format and suggests a certain set of rules. Because of this, maintaining quality and standardization becomes easy. REST has no standard rules. 
  3. The standard HTTP protocol of SOAP makes it possible to remain functional across multiple firewalls and proxies without getting involved in tedious modification. 
  4. When it comes to compatibility with extensions, SOAP has an upper hand as it can work wonderfully with WS-Addressing, WS-ReliableMessaging, WS-Coordination, and various other options, as suggested by W3C. 

API arhitectural styles

Organized in terms ofenveloped message structurecompliance with six arhitectural constraints
FormatXML onlyXML, JSON, HTML, plain text
Learning curveDifficultEasy
Use casesPayment gateways, identity managment CRM solution financial and telecommunication services, legacy system supportPublic APIs simple resource-driven apps

SOAP and REST Alternatives

Though developers still prefer using one of the above web services for their projects, the IT world is always open to new technologies and options. So if you are looking for a reliable alternative, there exist quite a few. Your options are –

A popular Query Language for data delivery to the client machine/user from the data-server, GraphQL can be a good choice in your case if your project is based on C++, Python, JavaScript, etc. Facebook, its creator company, has designed it to be very efficient at data fetching, writing, and subscription.

GraphQL’s messaging format is JSON, and it operates over HTTP. Though this fact may have made it look like REST, the truth is, it is even more capable on a few fronts. For example, you can send multiple requests in one call using GraphQL and avoid adding complexity to the operation alongside saving time.

JSON is quite well-known. It is an open standard for data object transfer/exchange and is already being used in a good number of applications. Its major benefit is its lightweight format that lets the requests take the data to and fro superfast. That’s majorly our reason for suggesting JSON as an alternative for SOAP and REST.

gRPC is a Google project. The system developed works upon HTTP/2 and is very modern in every regard. Whether you want to utilize it for your microservices-based solution or wish to ensure high-level performance from your application, gRPC can help you achieve it all. It is also great for connecting mobile devices of end-users to your app’s backend services. 

To your surprise, gRPC data/messages are even lighter than JSON objects and it offers more connection methods too.

SOAP vs. REST comparison table

Alright. While we walked you through all the major details regarding the 2 web services in-depth, you might still want to have a quick look into the major highlights related to the duo. So, here we present an insightful comparison table.

Comparison table

What is it called?Simple Object Access ProtocolREpresentational State Transfer
Server-side SessionsYes (for default configuration), it is Stateless. It can be changed to stateful.No, because it is stateful
How does it operate?It is driven by functionalities (services) for data fetching. Commands like getUser are used.Data is considered a resource.
Transfer ProtocolHTTP, UDP, SMP, etc.HTTPS
DesignIt is well-standardized and has a strict set of pre-specified rules.The architecture follows a not-so-strict guideline.
CashesNot usedUsed
SecurityAdheres to ACID properties and ensures enterprise-grade security that makes it ideal for sensitive data exchange and even financial transactions.HTTPS + SSL
Format accepted for messagingXMLJSON, XML amp; HTML.
Resource-consumptionIt is resource-intensive – Requires higher bandwidth and computing power.Requires much fewer resources.
How do they work together?It does not utilize SOAP due to its high architectural standards.This web service can utilize SOAP due to its standard for diverse usage.
Exposing TechniqueTechnicalities and methods can be viewed using WSDL.Its methods can be exposed using URIs.


REST and SOAP are among the most popular API protocols today. While REST is easy to work with and more commonly used, SOAP has a standard set of rules which is beneficial at times. Regardless of which approach you use, you will need to protect them appropriately to ensure the security of your users, any sensitive data passed, and your internal systems. The OWASP Top-10 is perhaps the most effective first step to ensuring you produce secure code. The addition of run-time API security layer designed for REST, SOAP and any other API protocols used will ensure your attack surface and risks are minimized.


How can I see the difference between the two on a code example?
Which one is better, SOAP or REST API?
What are the differences between SOAP API and REST?
What is REST API?
What is SOAP API?


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February 28, 2024
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