Unparalleled suite of productivity-boosting Web APIs & cloud-based micro-service applications for developers and companies of any size.


What Are the Types of APIs and Their Differences?

a person using the computer keyboard

Today, API is actively used in almost every business, both large and small. API (aka. Application Programming Interface) is an interface that allows multiple software applications to communicate with each other. For example, when an application wants to use a feature in another application, this feature becomes available thanks to the API. There are many types of APIs that businesses can use based on their business needs and needs. Types of API has different usage structure.

Types of API have been extended to developers and businesses to meet almost every need today. Moreover, there are many API protocols that developers and businesses can implement in all API types within the framework of these needs. In this article, we will first list the API types. Then we will introduce the API protocols that you can apply to these types and we will talk about their differences.

What Are the Different Types of APIs?

types of apis

Today, there are four main API types. These API types can help businesses in many ways, such as providing data privacy and outsourcing data.

Open APIs

The public API or open API is intended for use by any third-party developer. These APIs are programming codes made accessible with minimal restrictions. These APIs may be accessible via authorization methods such as an API key or may be fully open at the provider’s preference.

For example, a weather service provider’s public API allows developers and other businesses to access up-to-date weather information using this service. Third-party application developers using this API can access this service with a specific API key or authorization mechanism and provide weather information to their users.

Internal APIs

The type of API called private API or internal API is an API that is used only by the relevant internal systems and is not publicly accessible. This feature is the clearest feature that distinguishes it from the public API.

In-house development teams often use private APIs for efficient productivity, services reuse, sharing, and different platform integration.

For example, companies can only open the data in the CRM systems they use with private APIs inside the company.

Partner APIs

Partner APIs are APIs that businesses offer to their strategic partners. These APIs are not public. Additionally, they require special authorization for access. More specifically, while partner APIs do not offer as much public access as public APIs, they do not have as restricted access as private APIs.

For example, websites are the clearest example of using partner APIs. A website can use partner APIs to integrate with a particular partner.

Composite APIs

Composite API is an API type that combines multiple services or data into a single API. Developers create these APIs using the editing capabilities of API creation tools. In this API type, access to other APIs is provided through a single API.

For example, shopping sites can use composite APIs. A shopping site may want to integrate with the shipping company and perform payment transactions through the bank API. In this case, the shopping site combines the carrier’s and bank’s APIs using the composite API generator.

What Are the API Protocols?

api protocols

Today, there are many API protocols that can be used in API types. These protocols have different architectures and working principles from each other. In this section, we will introduce today’s most popular API protocols.


In its simplest definition, REST (Representational State Transfer) API is a web service that facilitates the exchange of data over the Internet. This web service enables developers to easily exchange data between different websites or applications. They can easily share data with each other. REST was introduced by Roy Fielding in his doctoral thesis in 2000.

REST API is an architectural structure that represents resources using the HTTP protocol and manages resources using HTTP methods (GET, POST, PUT, DELETE, etc.) using URIs (Uniform Resource Identifiers) to access resources.

Learn the 10 best free REST APIs for your next projects.


RPC API is a service designed for server and client communication. This API allows developers to easily create and launch multiple programs and services on a server. Generally, RPC requires developers or clients to run a block of code on a server.

There are two subtypes of RPC APIs:

  • XML-RPC: An XML-RPC is basically an RPC API that is encoded in return XML-formatted data.
  • JSON-RPC: A JSON-RPC is basically a hard-coded RPC API for returning JSON-formatted data.


SOAP (Simple Object Access Protocol) API is an XML-based messaging protocol. As a web service architecture, it uses XML format to encode data and sends it over the network to different systems. It serves as a widely used protocol for sharing data between different systems.

SOAP API, when used as a web service architecture, performs communication between a client and a server. The client creates a SOAP message and sends it to the server. The server receives the message, generates a response, and sends it back.

GraphQL APIs

The GraphQL API is a type of API that allows clients to get exactly the data they need from servers. This API prevents unnecessary data transfer and offers the client more optimized and faster communication. Finally, GraphQL APIs can provide access to multiple data sources through a single API.

For example, a social media platform can use the GraphQL API to provide users’ profile information, posts, followers, etc. The client may only request certain fields such as username, profile picture, and recent posts and the API will only return this data.

What Are the Differences of APIs?

In this section, we will talk about the differences between API protocols compared to REST API.

Differences Between REST and SOAP APIs

The main differences between REST and SOAP APIs are:

  • Architecture: REST web service offers a simple and lightweight architecture for implementation. SOAP, on the other hand, is a more complex XML-based protocol.
  • Data Format: REST APIs generally use JSON, XML, CSV, and many more data transfer formats while SOAP APIs prefer XML-based messages.
  • Performance and Scalability: REST is often the faster option due to its lightweight nature and stateless nature. SOAP, on the other hand, can be more complex and sometimes slower because it has more data processing and transaction security capabilities.

Differences Between REST and GraphQL APIs

The main differences between REST and GraphQL APIs are:

  • Requesting and Returning Data: Developers and developers using REST APIs must retrieve all of the data provided by a particular resource from the REST API server. Developers can make different requests to get all the data or just select some fields. GraphQL APIs allow clients to easily and quickly customize the data they need. The client can simply make a GraphQL query that specifies the data it is requesting.
  • Data Transfer and Network Traffic Management: REST APIs can cause unnecessary data transfer as they return all the data of a particular resource. It can increase network traffic especially when working with large data sets. GraphQL APIs, on the other hand, allow clients to request the data they need, which directly reduces network traffic.
  • Versioning and Backward Compatibility: REST APIs are often managed by versioning. When a new development is made, clients are required to upgrade to the new API version. GraphQL APIs, on the other hand, can ensure that changes made to the API schema work without affecting existing clients, thanks to their backward compatibility capabilities.

Differences Between REST and RPC APIs

The main differences between REST and RPC APIs are:

  • Architectural Approach: REST APIs have a resource-based architecture that runs on the HTTP protocol. The client performs operations using HTTP methods (GET, POST, PUT, DELETE). RPC APIs, on the other hand, are a set of protocols and methods used to make remote procedure calls. The client directly calls a procedure on the server and gets the result.
  • Data Transfer: REST APIs typically use lightweight data formats such as JSON, XML, and CSV, while RPC APIs typically use a more complex data format.
  • Transaction Structure: REST APIs perform CRUD (create, read, update, delete) operations on resources, while RPC APIs offer a more general transaction structure. The client can call a particular procedure on the server side and pass the parameters of the procedure.


As a result, there are many API types that businesses can use for APIs where they can exchange data with external systems. These API types can meet almost every demand and need of businesses. Furthermore, the API protocols available for each API type provide businesses with great flexibility.

Explore some useful APIs for your next development.

ipstack: Locate and Identify Website Visitors by IP Address

weatherstack: Real-Time & Historical World Weather Data API

fixer: Foreign Exchange Rates and Currency Conversion JSON API

Explore our highly equipped and free APIs, integrate them into your projects in just a few steps, and use them.

APILayer Banner


Q: What Are the Key Differences Between REST and SOAP APIs?

A: Firstly, REST (Representational State Transfer) API provides communication over URLs using HTTP protocol while SOAP (Simple Object Access Protocol) API provides communication over an XML-based protocol. Then, the REST API migrates data in JSON, XML, and more, while the SOAP API only supports XML format. Finally, the REST API is less complex than the SOAP API.

Q: What Are the Types of APIs?

A: APIs have more than one type according to their usage. The main types of the API are as follows:

  • Open API
  • Partner API
  • Internal API
  • Composite API

Q: What Are the Use Cases of Open API?

A: Open API is a public API. Below are some of the common use cases of the open API:

  • Quick Integrations
  • Mobile Application Development
  • Data Analysis and Reporting
  • Easy Content Sharing

Q: What Is the GraphQL API?

A: GraphQL is a query language that allows clients to strictly request the data they want in API calls. Unlike traditional REST APIs, it reduces unnecessary data overhead and eliminates multiple requests to get all the data required for a given application in a single request. As a result, GraphQL allows clients to select and retrieve only the data they need.

Q: Are the 90+ Web API Products Under APILayer Free?

A: Yes, they are. There are more than 90 Web APIs in more than 10 categories under APILayer. These APIs offer both paid and free subscription plans to their users, where free plans require an API key and have limitations on API calls.

Related posts

YouTube API Key | How Do You Get It in 2024? Tutorial + Examples


Cron Job Monitoring | The Perfect Way to Do it in 2024


Background Removal API | Automate the Image Editing Process


Current Weather API | A Complete Beginner's Guide in 2024

Leave a Reply

Your email address will not be published. Required fields are marked *