Cloud API: Categories, Features & Protocols

Traditionally in application development, Application programming interfaces or APIs are used to allow one application to use data and functionality of other applications. Same analogy which now flows into cloud computing, and we have been made familiar with one more term ‘Cloud APIs’. This article explains what cloud APIs are, why they are so popular, what type of cloud APIs are available? their usage and advantages 

What is Cloud API?  

A Cloud API is a software interface which allows developers to connect cloud computing services across. Just as application APIs let developers integrate and use data and functionality of one application into another application, in a similar fashion cloud APIs are written to support the cloud services of a one specific vendor or cross platform APIs let developers connect functionalities across one or more cloud service providers.

There are several ways to integrate infrastructure but where actually is the need for integration for your business is a key question to be explored and answered. 

Cloud API: Categories

There are four major areas where cloud computing will need to integrate with other cloud providers or platforms. 


PaaS APIs (service level) is also known as Platform as a service.  These service APIs are meant to provide functionality and access to the cloud environment. This may mean integration with databases, messaging systems, portals, and storage. Google App engine and Microsoft Azure are two prominent PaaS tools for application building on cloud.

SaaS APIs 

SaaS APIs (Application level) or Software as a service API as called. Their goal is to connect the application layer with the cloud and underlying IT infrastructure. CRM and ERP applications are good examples where APIs can be used as an extension to cloud at application level for the environment. Dropbox and Google Drive are well known cloud applications.


IaaS (Infrastructure level) or Infrastructure as a service API as called. These APIs control cloud specific distribution and allocation of resources. IaaS API could help in quick provisioning or deprovisioning of cloud resources. These APIs can be used in network configurations and workload (VM) management areas also. 

Cross Platform APIs

Many environments deploy hybrid cloud and may use more than one cloud service provider so there is a need for cross platform compatibility. HTTP and HTTPS API integrations are offered by several cloud providers so tenants can access resources apart from their primary cloud providers as well.  

Cloud API Protocols

The protocols which support cloud APIs include:

  • REST – RESTful APIs use HTTP protocol for functions such as creation, read, update, archive, and deletion of records
  • GraphQ! – it pulls all relevant data from several sites on a single request
  • SOAP (Simple object Access protocol) – APIs are using XML protocol for data transfer
  • JSON-RPC – is a type of remote procedure call which uses JSON formatting to transfer data instead of using XML 

The need to integrate multiple services and platforms created a new cloud API market. Many providers who ventured in this space are Apache (Citrix) CloudStack, Amazon web services API and Eucalyptus, Google compute engine, Simple cloud, OpenStack API and VMware vCloud API etc.

Features of Cloud APIs 

  • Automatically build, deploy, and scale cloud services
  • Empower distinct software platforms to interact with one another

Top most Cloud APIs

Let’s look at the top cloud APIs: 

  • Simple cloud API is a cross platform cloud API developed by Zend technologies and it serves PHP applications hosted on cloud.
  • Apache Libcloud API is complex technically and abstracts the difference between cloud service providers and unites them in a sequence. it presents a python library which permits cloud resources to work together
  • Amazon web services API gateway is used for generating and managing APIs which can integrate with AWS and other web services. E-g.- AWS Cloud Control, Amazon EventBridge and Amazon API Gateway 
  • HubSpot API is used to create custom integrations allowing HubSpot to work with apps like zoom or Mailchimp 
  • Box API authorizes developers to manage and interact with their box files. 
  • Google Cloud APIs – Google Compute Engine API (create & run VMs on Google Cloud), Google Storage Transfer API (data transfer from an external source to Google Cloud) and AutoML API (helps to create machine learning models) 
  • Azure APIs – like Azure Communication Services, Azure Cognitive Services and Azure API Management.


The global cloud API market size was valued at $417.3 million in 2018 and it is projected to grow to $1,786.1 million by the year 2026. Cloud APIs are considered a big leap where applications use APIs to communicate to end users with flow of information. They serve as interface and gateway to provide indirect and direct cloud infrastructure and software services to customers. 

APIs are bringing agility into the cloud. The SaaS API segment is the highest contributor in the cloud API market and projected to remain so due to its software centric approach across multiple industry verticals. In addition, rise in use of mobile applications is supporting growth of SaaS API segment 

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