In the high-tech world that businesses operate in today, the number of software solutions a company regularly uses is steadily increasing. In fact, in 2021, the average number of SaaS applications an organization employed was 110. For reference, just in 2015, that number was 8.

Average number of SaaS applications used by organizations worldwide

With so many disjointed solutions being operated, it’s easy to see why API development services have become so in-demand. After all, there are plenty of benefits to obtain from letting software apps smoothly communicate with each other.

However, there’s no one-size-fits-all approach when it comes to the API architecture. Everything depends on the project you’re working on, existing tech stack, and sometimes even developer preferences.

Over the years, various API technologies were released to facilitate data exchange between the frontend and backend, each with its own pros and cons. Hence, picking one over the others can be a daunting and confusing endeavor.

Today, we will try to dispel some doubt and help you determine which API technology you should choose — SOAP, REST, gRPC, or GraphQL. We’ll cover when to use GraphQL over REST, gRPC instead of GraphQL, and so on. That way, you’ll be able to make an informed decision.

The Role of APIs in Microservices

Before we decipher the differences between GraphQL, gRPC, REST, and SOAP, it’s important to mention the role of APIs in microservices. You may have heard the two terms used frequently in discussions about software architecture and integrations.

APIs and microservices are vital to modern web app development. Hence, understanding both concepts is important for IT teams and business leaders alike. An API is a specific part of a web solution that allows it to communicate with other IT tools. A microservice, on the other hand, is a way of developing an app by creating separate modules where microservices can run and communicate through APIs.

Learn more about Microservices and Web Services

In short, the two are often mentioned in tandem because microservices use APIs to communicate with each other. Of course, services can also exchange requests and responses through an event bus like RabbitMQ or Kafka, but that’s a separate topic.

So, if your project is set to employ a microservices architecture, APIs are likely to play a big role in it. Thus, choosing the best suitable one among SOAP, REST, GraphQL, and gRPC is crucial.

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Understanding SOAP vs. REST vs. GraphQL vs. gRPC

API Timeline

As we have established, there is a variety of API formats and no single one is a clear winner since each has its own pros and cons. So, let’s take a look at the four most well-known options in the order that they were released and see why you may want to pick one or the other for your next project.



The Simple Object Access Protocol (SOAP) is the oldest of the four API technologies we’re going to discuss today. In essence, it is an XML-based web communication protocol that allows for the exchange of information when implementing web services in computer networks.

Typically, SOAP is used with the Web Service Description Language (WSDL), which allows for the inspection of a web service that supports SOAP and simplifies programming. Plus, it relies on application layer protocols like SMTP, TCP, UDP, or, most commonly, HTTP.

The message structure of SOAP is rather lengthy and consists of an “envelope” tag to indicate the start and end of a message, a “header” with optional attributes, a “body” with the actual request or response, and a “fault” to indicate information about errors that may have occurred during processing.





Representational State Transfer (REST) is an API technology that came soon after SOAP when Roy Fielding described it in his Ph.D. thesis in 2000. Currently, it’s likely the most common API style being used, especially in microservices architectures.

REST can be developed in various programming languages and supports multiple data formats, typically JSON and XML. A RESTful architecture should be aligned with the following six constraints:

  1. Uniform interface
  2. Client-server decoupling
  3. Stateless
  4. Cacheable data
  5. Layered system architecture
  6. Code-on-demand (optional)

Even with these architectural constraints, REST isn’t as strict as the previously discussed SOAP.


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GraphQL is an open-source query language for APIs that was internally developed by Facebook and subsequently released to the public. It allows clients to request any specific data that is needed, which enables the return of predictable results.

Unlike REST, GraphQL has its own specification that can be implemented using a variety of programming languages. For some, this is a clear benefit of GraphQL over REST. Additionally, this technology uses queries, mutations, and subscriptions for sourcing data, not HTTP methods that REST relies on.

In our experience, GraphQL is being relied on more and more frequently. At times, simply because it’s the most optimal option for the chosen tech stack.

GraphQL Use Cases

For instance, our team had a project in the blockchain sphere, in which a decentralized exchange platform had to be developed. Our specialists relied on The Graph API, a second-layer API solution for blockchain, to acquire the needed data. As The Graph automatically generates a GraphQL endpoint, it was the most optimal technology for us to complete the project with.

Another example of GraphQL usage was on a project where our team was working on creating universal grid tables that could obtain data from API endpoints provided by Hot Chocolate library. Naturally, to complete the task, we chose to use Hot Chocolate, an open-source GraphQL server for the Microsoft .NET platform.

It allowed us to quickly get the needed features for the grid tables because it came with ready-made filtration, sorting, and other options that the Client was looking for.

GraphQL Pros

GraphQL Cons



gRPC is an open-source Remote Procedure Call (RPC) framework that was created by Google, can run in any environment, and be implemented in a variety of languages.

gRPC is contract-based and uses the Protocol Buffers binary data format. It requires both the client and the server in data exchange to have access to the same schema definition.

Additionally, gRPC is based on the HTTP/2 protocol. It supports any amount of requests and responses over a single connection. Plus, the communication is bidirectional. This implies that a single connection can send both requests and responses at the same time, allowing for latency reduction.

gRPC Use Case

On an ongoing project, Velvetech’s developers had actually entirely embraced gRPC. The team was tasked with developing an online marketplace for long-term senior care residences and decided to rely on the gRPC protocol as it allows for speedy frontend-backend interactions which the Client was looking for.

The biggest advantage of using gRPC for the long-term care booking platform was that it provided streaming and duplex communication capabilities. Thus, allowing the team to build optimal interactions between the frontend and backend.

gRPC Pros

gRPC Cons

How to Choose the Right API Architectural Style

How to Choose the Right API Architectural Style

Now that we’ve gone over the various API styles, you might be asking yourself, how do I make sure I choose the right one for my project? Well, unfortunately, it’s hard to give a clear-cut answer.

You see, every API project has different needs and requirements. Thus, as we’ve already said, there’s no one-size-fits-all approach, it can really be a challenge to choose the API to set. However, typically, the choice of an API architectural style depends on the following factors:

Everything depends on your own priorities, needs, and goals. Knowing the pros and cons of each API style can empower you to make the best decision. However, don’t forget that these technologies can also be mixed and matched in some cases. Particularly, if your app’s architecture has multiple APIs that are to be used for separate purposes. For instance, when you have internal and public-facing APIs.

So, whatever choice you make doesn’t have to be set in stone and used universally. Just keep the following comparison table in mind when making your decision, or reach out to experienced software development vendors for a consultation.

Envelope message structure Compliance with six constraints Local procedure calling Schema and type system
XML only XML, JSON, HTML, text JSON, XML, Protobuf, Thrift, FlatBuffers JSON
Stateful, stateless Stateless Stateless Stateless
Caching module HTTP caching Custom caching
Good for
Payment gateways, CRM software, fintech tools, legacy system support Public-facing interfaces Command and action-oriented APIs, internal communication in large microservices systems Mobile APIs, microservices

Get Help With Picking an API For Your Project

We’ve covered a lot of ground today. It is evident that choosing the right API for your software project might not be the most straightforward endeavor. However, it is definitely something you need to approach seriously as it can affect the success of your solution and impact performance and scalability.

At Velvetech, we have spent years delivering great API development services to clients from a vast range of industries. So, feel free to reach out to our team if you are looking to ensure connectivity across all of your business applications. We’ll be happy to help you with API development.

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