What is a REST API?

The first mentions of REST come from the works of Dr. Roy Fielding, a researcher in computer science, in his dissertation entitled “Architectural Styles and the Design of Network Based Software Architectures”. Dr. Fielding introduced the basic concepts of REST and additional complimentary details. Spanning 180 pages, the paper went over how software developers could use existing technology to make robust and powerful tools while keeping things simple. This paper laid the foundation that led to the formation and evolution of simpler APIs – including REST.

REST On the Rise

The earliest adopters of simplified APIs were ecommerce platforms. The first major and publicly available REST API was put out by eBay on November 20, 2000. Limited to a few partners originally it set the benchmark for any future APIs to come out. Amazon.com published their own API in 2002. Then came social networks, with first Flickr (2004), then Facebook (2006), and Twitter (2006).

These APIs served multiple purposes. First – they allowed the creation of complimentary platforms. Suddenly eBay was no longer just the website eBay. It became a data repository for anyone with the ability utilize the API, spreading eBay’s reach far around the Internets, giving birth to more online shops, all depending on eBay. This, in turn, increased the value of eBay, generating more sales for eBay, more advertising spend, and a continual stream of people joining to build their own tools and shops on top of their API. Although eBay’s popularity has declined in the past years, their API was a revolution and changed the way e-commerce worked forever. 

Second – they allowed more control over a company’s data and with lower costs. Scraping (using a robot to go collect information on a web page) was a costly thing for eBay – and for most companies. By introducing an API, they could greatly reduce the amount of robots (software programs that searched, indexed, and stored metadata about their site) they needed to use, lower costs, and programatically control access to their data. Through the use of API keys or tokens bad actors (people abusing the API) could quickly be evicted, while people with good business cases saw a standardization in how a company’s data could be accessed dependably.

While more companies were building their own APIs to give access to their own services – e.g. Cloud Computing – one saw more potential in that – Amazon. Amazon originally built Amazon Web Services (AWS) to guarantee access to their online shops. Over time Amazon began reorganizing itself in smaller entities, all connected together by APIs. At first, this gave them greater flexibility, allowing teams to perform changes rapidly, as long as they didn’t change the outside-facing API.

Then, in March 2006, Amazon changed everything. They launched AWS with a new purpose: providing a cloud-based computing platform that could be used to rapidly build and grow web-based services (like Dropbox). AWS services were no longer restricted to Amazon’s internal use The first service launched, Amazon S3, is a mass storage service. By making it accessible through a REST API and selling access to computing resources, people could now start building not just tools around platforms, but platforms themselves. Amazon EC2 would provide computing resources in the cloud, allowing people to run servers, move to more powerful machines when needed. Gone were the days of needing to rent space in a server room and buying your own hardware. You could now launch new servers in the span of seconds, get reliable backups and content delivery, all accessible through simple APIs. Today, Amazon is the biggest cloud provider in the world, showing that their strategy worked. While not responsible for the rise of cloud computing, REST APIs, through their ease of use, certainly contributed to a faster growth of it.

No rest for REST APIs

Platforms would once again take the spotlight a few years later, with the rise of smartphones. Applications were no longer only available via a web browser on a computer – they exploded across Google’s Android and Apple’s iOS as both companies introduced online marketplaces that made downloading and installing smart phone apps simple and straightforward.  These apps would need back-end dependable, scalable computing resources as they experienced rapid growth – and AWS was there to answer the call. Many apps today are not only built using REST APIs, but have their own REST APIs as well.

Today, REST APIs are everywhere. To say they have won the API war in not an understatement. And while they may one day be dethroned themselves by newcomers (gRPC, GraphQL, etc.), they currently stand at the top of the API game and – because of their ubiquity – will likely stay there for a long time.

Today having a strong understanding of REST APIs is expected of any software developer as most SaaS (Software as a Service) tools are built with with their own REST APIs. And REST APIs are everywhere. As of 2018, an estimated 85% of APIs online were REST APIs (or a close variant). Billions of requests are made to these APIs every day – and they drive interoperability not only on the web, but with offline products like Nx Witness VMS and Nx Meta VMP.