Understanding the Difference between Swagger and OpenAPI

Two big players in the API industry are the API tool developer Swagger and the organization called the OpenAPI Initiative. By virtue of their history, these two brand names are frequently tied to one another. Some who are new to the ecosystem of the API industry also tend to make the mistake of interchanging the two. Their close ties notwithstanding, however, Swagger and OpenAPI are different entities. API stakeholders should understand them as contributing in separate ways to the field of API development.

To help distinguish between Swagger and OpenAPI, and how they work with other technologies like the Stoplight OpenAPI editor, here’s everything you need to know. This article details the history of Swagger and the OpenAPI Specification, otherwise known as OAS. Then we’ll learn of their mutual impact on modern APIs and what stakeholders can expect from the two entities in the future.

Swagger, the OpenAPI Initiative, and Their Impact on the API Industry: A Timeline

Both Swagger and OpenAPI began as the brainchild of Tony Tam, a software engineer for the online dictionary service Wordnik. Tam used the earliest iteration of what’s now known as OAS in order to describe the JavaScript Object Notation (JSON) API of Wordnik. “Why WADL when you can SWAGR” was the coy response of Swagger’s technology to its predecessor, the Web Application Description Language. In OAS, Tam was able to devise a framework for describing APIs that would soon evolve into an industry standard.

Tam published the open-sourced Swagger Specification in 2011 and followed it up with a minor refinement in 2012. The first formal specification documents, in the form of Swagger Specification 1.2 and Swagger Specification 2.0, were released in 2014. Upon widespread usage in the API community, Swagger Specification was consequently adopted by IT thought leaders giant SmartBear Software in 2015. Two years later, in 2017, the Swagger Specification became the property of an open-governance group called the OpenAPI Initiative.

This is the product now known as the OpenAPI Specification, and it is currently on its third version. It also enjoys a wide following among API developers as the go-to format when describing RESTful APIs.

What Swagger and OpenAPI Offer Today

Even after its donation for a signature specification framework to the OpenAPI Initiative, Swagger is still very active today. The easiest way to distinguish Swagger’s current work from OpenAPI Specification is this: while OAS provides the specification, Swagger provides tools for its implementation.

OAS is a vendor-neutral specification that can be implemented with various toolsets. But the brand that comprises some of the most well-known toolsets for implementing OAS is none other than Swagger. Other companies, like Stoplight, have supplemented the great work done by Swagger and OpenAPI. The rise of intuitive and OAS-compliant OpenAPI editors like Stoplight’s prove that a robust economy is happening around API specification.

Final Words

To recap, here’s what you need to remember about Swagger, OAS, and the OpenAPI Initiative:

  • The OpenAPI Specification, or OAS, is the description format formerly known as Swagger Specification.
  • The governing body in charge of promoting OAS and leading the community of OAS users is the OpenAPI Initiative.
  • Swagger is now a major tool developer for the vendor-neutral OpenAPI Specification, and other API development companies contribute to the current network of OAS-related resources.

The next time you encounter Swagger, OpenAPI, and their contemporaries, you will know the unique impact they have on the industry. You will also know where to look, and what to refer to, when you’re searching for your own API development tools. Be sure to keep in touch with the latest updates on OAS, and expand your toolset to create excellent OAS-driven APIs.


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