Web Service vs. API: what are they, and how are they different?

The terms web services and APIs are frequently used, but may cause confusion. While they do share some similarities since they both facilitate data transfers between two software components, they shouldn't be assumed as the same thing.

In this article, we'll examine each of them individually and examine the components that make them up, as well as compare the key differences between web services and APIs.

What are web services?Anchor

The answer to what web services are depends quite a lot on the context of the ongoing conversation. In one context, we can see web services as payment ecosystems, storage services, email services, cloud functions, text-to-speech converters, etc. These services are individual systems in themselves that save you a lot of “building up from scratch” when you are coding applications. Anyone who wants to use them can sign up for it in a pay-as-you-go model.

Going back to the 2000s, in another context, we can say that Web Services are a set of protocols and standards that facilitates data exchange between different software applications. We will be talking about this context throughout the article.

Web service componentsAnchor

Below are the components that are needed to build a web service.

• SOAP - Simple Object Access Protocol
• RDF - Resource Description Framework
• UDDI - Universal Description, Discovery and Integration
• WSDL - Web Services Description Language

Building web services need strict rules to be followed, and they tend to be more process intensive and code-heavy. Web services are about the same as SOA (Services Oriented Architecture) and are primarily based on standards such as XML-RPC and SOAP. Generally, SOAP is used, and the exchange of data happens in XML over the HTTP protocol.

Main features of web servicesAnchor

• Accessed through a network connection.
• Loosely Coupled.
• Use SOAP, UDDI, WSDL, etc for communication.
• Does not have a lightweight design.
• Runs on HTTP Protocol.
• Data exchange is XML Based.

Today, web services are mainly used in legacy B2B systems or when there is a need to integrate with systems running on an old software architecture.

What is an API?Anchor

The term API refers to an Application Programming Interface, similar to web services when two software components need to communicate with each other they can do it with the help of an API. APIs leverage technologies and follow a protocol to facilitate communication. There are different APIs like GraphQL, REST, WebSocket APIs, RPC APIs, and more. All APIs have their own set of protocols and definitions, so each API type will have a different operating mechanism.

Compared to web services, APIs are more accessible, they do not need you to be in a specific network to run, they have a lightweight architecture, and they are easier to implement. APIs can use any kind of communication convention and are not restricted like a web service. We can say that API is a broader category, whereas web services are a specific flavor or type of API.

It is often assumed that APIs are web APIs (APIs available over the Internet). However, APIs can also be exposed through local files to allow two local applications to communicate. Since the two applications are on the same device, there is no need for a network.

API componentsAnchor

APIs have a comparably lightweight architecture.

• Client and Server
• Request Response Formats - API Contract

To learn more about the internal workings of an API we recommend checking out this article.

Main features of APIsAnchor

• Data exchanged is generally JSON based.
• Does not require a specific network to access.
• Lightweight architecture.
• Highly configurable.
• Easy to implement and use.

APIs are the broader category and are widely used for facilitating communication between software applications today. They support major use cases for building public-facing or auth-controlled application interfaces, with configurable business logic in a less complicated manner compared to web services.

Web Services vs. APIs, a side-by-side comparisonAnchor

Wrapping upAnchor

Ultimately, APIs can be considered to include web services, but are not limited to them. The lightweight architecture makes APIs more accessible to a broader extent.

Although there are subtle differences between these 2 concepts, it's critical to distinguish them so that you can better understand your product's integrations.