Introducing KaiZen OpenAPI Editor: the open source Eclipse editor for OAS 2.0 & 3.0

Tanya Fesenko
Posted by
Tanya Fesenko on Sep 20, 2017 10:19 AM

KaiZen OpenAPI Editor is an Eclipse-based editor for the OpenAPI Specification (OAS). OpenAPI v2, formerly known as the Swagger specification, is the most widely used and supported API description language, and OpenAPI v3 is a new major version, released in July 2017 with significant new features and improvements.

KaiZen OpenAPI Editor supports both OpenAPI v2 and v3, and it's available now on the Eclipse Marketplace.

Why would I want to edit a Swagger-OpenAPI spec if I can generate it from code?

It’s true, many people still start with implementation, generate an OpenAPI file from code, and use the generated file as the source for Swagger-UI. But we believe API Contract as Code yields better results by first carefully designing the API, evolving the design with feedback from users who interact with an API mock service, and generating executable code in an agile, iterative development lifecycle.

The good news is that the OAS v3 specification is much more readable and refined than that for v2, so creating OpenAPI files for v3 is easier (and more pleasant) than ever!

OK, so what capabilities does KaiZen Editor provide?

By now you have a few choices for OpenAPI 3.0 editing, including the popular Swagger Editor. KaiZen OpenAPI Editor offers all the cool features that many other editors provide, such as code assist, validation, and code folding, right inside your Eclipse IDE.

And KaiZen Editor brings some unique new features to the party. For starters, you can see the general structure in the outline view, which is particularly useful for large files:

KZOE Outline View.png

Code templates help to create a new element in just a few clicks. For example, schema definitions are core components of OpenAPI v2 documents, and and they have some new capabilities in v3. Here, I am creating a new schema definition:


We provide code templates for new OpenAPI v3 elements, as well as familiar ones you'll recognize from OpenAPI v2. A Callback is a new element introduced in OpenAPI v3. Look how easy it is to create a new Callback in KaiZen OpenAPI Editor:


It looks like Eclipse. Is it Eclipse?

Yes, KaiZen OpenAPI Editor is an Eclipse-based editor, it means that it works seamlessly with other plugins, e.g. plugins for version control, task managers, or programming languages.

It’s so convenient to design your API, generate code and extend generated code in the same editor, we even created a video demonstrating how to do it in our commercial product, RepreZen API Studio.

API Contract as Code Demo Thumbnail.png

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OAI and Eclipse Memberships.png

By the way, we're proud to have joined the Open API Initiative and the Eclipse Community this year.

These are both amazing groups of people, promoting open source and open standards, with lots to offer. We encourage you to learn and get involved!

I want to install KaiZen OpenAPI Editor. How can I get it?

It’s very easy, and you have loads of options:

Nice! How is it implemented?

KaiZen OpenAPI Editor extends YEdit, an Eclipse editor for YAML files. Code assist, outline view, and quick outline are based on aJSON Schema for OpenAPI v3. While there is no official JSON Schema for OpenAPI v3, Tim Burks from Google provided a JSON Schema which he generates from the specification markdown file. Isn’t that cool? We use Tim’s JSON Schema and sometimes provide feedback and adjustments to the schema.

Wow, can I get involved & contribute?

Absolutely, all contributors are welcome! KaiZen OpenAPI Editor is an open-source project hosted on GitHub under an Eclipse Public License. You can submit new issues, provide documentation, or fix bugs. We will happily review them ASAP.

Topics: API, REST, eclipse, Swagger, OpenAPI, SwagEdit, KaiZen OpenAPI Editor, Open Source


At RepreZen, we're building our business on two things:  thought leadership in API design, and great conversations.

This blog is one of many places where we'll have illuminating, mutually enriching conversations with our customers, partners, and the software community at large.  Please chime in with your thoughts and let's get started!

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System Requirements


RepreZen API Studio runs on the following operating systems:

  • 64-bit Windows 7, 8.0 and 8.1
  • Mac OS X 10.7 or higher
RepreZen API Studio requires 64-bit Java 8 or higher.