SOAP and REST APIs: Pros, Cons, and TrendsSOAP and REST APIs: Pros, Cons, and Trends

Updated: February 2nd, 2024


SaaS applications are becoming increasingly popular among businesses, with companies using more than a hundred for their operations. This has resulted in high demand for APIs, which facilitate the integration of applications in order to sync all data and gain valuable insights for decision-making. REST and SOAP are the most popular API paradigms and have become the "standard" during the last two decades. In this article, we will dive into the specifications and highlight the advantages and drawbacks each one presents.

REST and SOAP were introduced in the late 1990s and early 2000s. Having been around for more than two decades, these have become the most used specifications for accessing web services. Both share some similarities but also have significant differences to consider when picking one for your project. Below, we will briefly describe what is an API and web service before we discuss the specifications and differences between the REST architectural style and SOAP messaging protocol.

What is an API?

API stands for application programming interface and is a software interface that allows two computer programs to communicate and transfer data. Unlike user interfaces, which connect an application to a person, APIs connect applications to other applications or software. Information is shared through requests and responses via internet protocols such as SMTP and HTTP, among others. These requests are known as API calls or API requests, and they are the medium used to interact by sending messages over a server asking for a service or information to another API. Programmers use tools and services from an API to make the "calls", also known as endpoints. API specifications, which are documents that specify how to use the interface, define and explain how to use the endpoints.

APIs can be custom-built for specific requirements, or standard, which allows interoperability with other systems. There are APIs for websites, known as web APIs, as well as for software libraries, programming languages, computer hardware, etc. APIs generally are created for internal or public use, such as Google Maps for business listings. In order to build our own API, there are several API formats we can choose. For this article, we will focus on the most popular, REST and SOAP. Each architectural style has advantages and limitations, so it's best to evaluate which is more suitable for your needs.

What is a Web Service?

Web service is a broad term for a type of internet technology encompassing software that provides web standards and standardized protocols to interoperate and exchange data through the internet or private (intranet) networks. In other words, a web service is a software system designed to support interoperable machine-to-machine interaction over a network. Web services use XML to encode all application-to-application communications, which can be programs, objects, messages, or documents. The two primary architectural styles and protocols for accessing web services are REST and SOAP, which we will discuss below.

Simple Object Access Protocol - SOAP APIs

SOAP stands for Simple Object Access Protocol and it is an official messaging protocol created for the exchange of information from one computer to another using XML (Extensible Markup Language). The SOAP protocol is standardized with built-in rules and sends messages by using other protocols such as SMTP and HTTP. SOAP is often used in conjunction with Web Services Description Language (WSDL) as it provides a way to describe the interface of a web service, including the location of the service and the methods it supports. This makes it easier for clients to consume the web service and understand how to interact with it.

Originally, Microsoft developed this protocol because of the challenges presented by old technologies such as CORBA and DCOM, which are not the best for the exchange of information over the internet. With SOAP, multiple apps built on a variety of platforms using different languages can communicate with each other. SOAP has three key features: extensibility, meaning you can choose which standard protocols you want to use; neutrality, meaning SOAP is neutral and can operate over HTTP, FTP, SMTP, etc.; and independence, meaning SOAP is programming language and platform independent.

Some advantages of using SOAP are that it has superior security than REST, with WS-Security and ACID, HTTPS, and SSL. This enterprise-grade security makes it a better choice for transmitting sensitive information.

KingswaySoft's SSIS HTTP/Web Services and JSON/XML components enable you to easily integrate a SOAP API with any other API, application, or data source.

Representational State Transfer - REST API

On the other hand, REST is not a protocol such as SOAP, but an architectural style with a set of guidelines for distributed hypermedia systems. REST stands for Representational State Transfer and uses the HTTP protocol for data exchange. When developers build web services using REST, these are called RESTful web services.

REST guidelines are not strict procedures but recommendations that developers can implement according to their requirements. This makes REST lighter and improves web services performance with faster page load speeds, making it the popular go-to solution for mobile applications. Another significant difference is that REST is not constrained to use XML but allows other messaging formats, such as JSON, HTML, and plain text.

To create a REST API, you need to follow six architectural constraints:

  • It requires a uniform interface
  • The client and server should be independent
  • It needs to be statelessness, with each request having all the information required by the server
  • Should have cacheable resources
  • It requires a layered system
  • When necessary, it should have executable code

REST was built to address the limitations of SOAP with a more flexible architecture. Compared to SOAP, REST is more flexible. Some advantages are that it has easy-to-understand standards, is easier to learn and use, is fast and efficient, uses the widely adopted HTTP standard, and has smaller message formats such as JSON. On the other hand, REST is not as independent as SOAP due to its required use of HTTP status codes.

OData for REST APIs

It is worth mentioning OData when discussing REST APIs. OData, which stands for Open Data Protocol, is an open protocol (OASIS standard) that defines the best practices for creating and using RESTful APIs. OData lets you focus on your business logic while building RESTful APIs without the need to worry about the multiple approaches to define request and response headers, HTTP methods, status codes, media types, URL conventions, payload formats, query options, and more.

As previously mentioned, OData APIs are built on top of the RESTful architectural style. KingswaySoft's Premium OData and REST SSIS Components simplify working with any REST or OData-based service endpoint, allowing you to easily read or write to a REST or OData instance. Learn more about the Premium OData SSIS Components and the SSIS REST Connectors to integrate APIs and streamline your ETL process.

Alternatives to REST and SOAP

There are other alternatives to REST and SOAP. In recent years, tech giants Facebook and Google developed their own API specifications, GraphQL and gRPC, respectively. After some time, these modern specifications became open-source and are gaining popularity, being used by other big companies, such as GitHub, Intuit, Cisco, and Square. Additionally, Microsoft's Microsoft Graph, a pivotal API, provides developers with a unified endpoint for accessing a diverse range of Microsoft 365 services. 

GraphQL APIs

Originally conceived as a query language for APIs within Facebook's domain, the GraphQL specification has evolved into an open-source powerhouse, stretching its influence far beyond its initial confines. This transformation has positioned GraphQL as a dynamic and versatile solution, now embraced by other major companies such as Pinterest and Shopify.

GraphQL is commonly compared to REST when developing web APIs and has some advantages, such as getting in a single request all the data your app needs, unlike REST APIs, which require loading from multiple URLs. GraphQL is used to communicate with the server and allows clients to determine the data structure required, thus avoiding the return of large amounts of data. GraphQL supports reading, writing, and subscribing to changes to changes.

GraphQL enables efficient data retrieval in a single request, eliminating the need for multiple URLs, unlike REST. It empowers clients to define the required data structure, preventing unnecessary data transfer. GraphQL supports reading, writing, and subscribing to changes, providing flexibility in data operations.

KingswaySoft's SSIS GraphQL Components allow you to effortlessly connect GraphQL APIs with other APIs, applications, or data sources.


Another popular alternative is gRPC, which stands for Google Remote Procedure Call. It is a modern RPC framework developed by the tech giant Google and used for building APIs. Such as GraphQL, gRPC also is language-agnostic and can be implemented in different programming languages. Some of the advantages of using gRPC are the high performance and the lightweight of the RPC framework.

The specification uses HTTP/2, protocol buffers, and some features include authentication, bi-directional streaming, pluggable auth, tracing load balancing, and health checking. gRPC is frequently used for connecting services in microservices applications. Today the specification is used by many well-known companies such as Netflix and Dropbox.

Microsoft Graph

Microsoft Graph is a powerful API offered by Microsoft that serves as the backbone for developers seeking to bridge the gap between their applications and Microsoft 365 services. As Software as a Service (SaaS) applications gain prominence in organizational workflows, the demand for effective APIs has surged. Microsoft Graph offers a unified endpoint that empowers developers to effortlessly access resources such as user profiles, emails, calendars, and files across the Microsoft 365 ecosystem.

Microsoft Graph

With its ability to simplify development processes and enhance user experiences, Microsoft Graph has become a popular tool for building interconnected and efficient applications within the Microsoft Cloud environment.

KingswaySoft's SSIS Microsoft Graph Components allow you to effortlessly connect Microsoft Graph APIs with other APIs, applications, or data sources.

Which One Should You Use?

Some engineers argue that they are not comparable since they are different technologies; Simple Object Access Protocol, or SOAP, is a messaging protocol, while REST, or Representational State Transfer, is an architectural style. Nevertheless, they are two different approaches that help solve the same problem: to interact with web services. We will now discuss the advantages and limitations of each one.

SOAP Advantages

When it comes to the SOAP protocol, some of its advantages are that it is language and platform-independent, it is standardized, it provides extensibility with WS standards, it is ACID compliant, and it includes error handling.

SOAP gives you control over the end-to-end process, such as server-to-server communication for an organization's internal use. It supports both stateful and stateless operations, while REST is designed to be stateless for simplicity. Also, when properly configured, it is more secure as it uses WS security in addition to HTTPS and SSL support. SOAP offers more flexibility when choosing transfer protocols to handle different scenarios, such as HTTP/HTTPS, TCP, FTP, UDP, SMPT, etc., while REST must use HTTP/HTTPS. SOAP also counts with built-in ACID compliance, which protects database integrity, and makes it superior for sensitive transactions. In terms of error handling, REST lacks a standard messaging system and relies on retrying communication failures, while SOAP's built-in successful-retry logic provides end-to-end reliability.

If your priority is standardization, tighter security, more flexibility with transfer protocols, and you are not concerned with the size of the messages, SOAP would be the right choice.

REST Advantages

SOAP's design is more complex and not as light and fast as REST, which requires fewer resources. Being more lightweight and flexible, REST can handle the transmission of messages over to many low-memory and low-processing-power devices connected to more than one service.

Because of HTTP protocols, REST is much simpler than SOAP, and is compatible with browsers thanks to its JSON data format. Being able to operate with not only JSON, but other formats such as XML, HTML, and more, it is highly flexible when structuring the messages, formats, and client and server scale. REST architecture is based on a client-server principle, which makes the user interface more portable, as it is separated from the data storage tasks. Moreover, all components use a single uniform interface, simplifying how the applications interact with the API.

Also important, HTTP caching is only possible on REST; SOAP caching would require configuring an additional cache module. This enables the storage of non-dynamic information on the client side, improving loading speeds. REST APIs that operate with JSON files don't need the overhead text and code blocks found in SOAP's XML, significantly reducing their size and making processes and transfers easier and faster. A simple analogy is frequently used to explain this: SOAP is an "envelope", and REST a "postcard". Postcards (REST) are easier to read and consume less paper, meaning less bandwidth; SOAP uses an envelope-style message format and needs to be "unwrapped" to see the message inside, thus increasing bandwidth use.

What To Choose: SOAP vs REST

If you are looking for flexibility and efficiency, REST is more suitable. REST has a smaller learning curve and a larger community to get faster answers to problems. REST has superior performance while it is highly scalable. However, it has the downside that it can get bogged down. This is one of the reasons why GraphQL was developed. SOAP requires a more in-depth understanding of standards and WS protocols, with a smaller community to get help. However, if high-level security, standardization, and transfer protocol flexibility are a priority, SOAP has the potential to provide it and would be more suitable for your project.

Easily Integrate your REST and SOAP APIs

Building a SOAP or REST API integration for your organization can be extremely complicated and expensive. Here is where KingswaySoft becomes a practical and cost-effective solution for your API integrations. Using KingswaySoft's integration solutions, you can sync any API or data source without writing a single line of custom code. Packing more than 300 premium tasks and components, these powerful ETL tools will remove the complexity of API integration projects.

Thousands of enterprise clients from over 100 countries rely on our no-code SSIS Integration solutions to integrate data with various application systems to drive business efficiency and leverage information assets.

To read more about our SSIS data integration solutions click here.

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About KingswaySoft

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