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A library that simplifies OpenAPI integrations. This library handles the minutiae of loading OpenAPI documents (local and remote), resolving references (local, remote), building an object model and providing you with a rich set of APIs for things like OpenAPI document validation, request/response validation, etc. For more details on the available APIs, please view the API Documentation.

master will always be built to support the latest release of OpenAPI, which right now is 3.x. Previous versions are in their own respective v{N}.x branch:

  • 3.x Support (WIP): master
  • 2.x Support: v2.x


sway is available for both Node.js and the browser. Installation instructions for each environment are below.


sway binaries for the browser are available in the dist/ directory:

Note: I realize these binaries are big and I'm working on making them smaller. Unfortunately, some of this is out of my control without rewriting some of the core features provided by third-party libraries currently contributing to the size issue.

Of course, these links are for the master builds so feel free to download from the release of your choice. Once you've gotten them downloaded, to use the standalone binaries, your HTML include might look like this:

<!-- ... -->
<script src="sway.js"></script>
<!-- ... -->


Installation for Node.js applications can be done via NPM.

npm install sway --save

API Documentation

The sway project's API documentation can be found here:

Swagger Resources

Swagger Validation

Swagger validation can be broken up into three phases:

  • Structural Validation: This is where we use the Swagger provided JSON Schema linked above and use a JSON Schema validator to validate the structure of your Swagger document
  • Semantic Validation: This is where to do validation above and beyond the general structure of your Swagger document. The reason for this is that there are some situations that cannot be described using JSON Schema. There are also situations where the existing JSON Schema for Swagger is broken or not as strict as it could be.
  • Custom Validation: This is user-configurable validation that typically fall into stylistic checks.

Structural Validation is the only type of validation that occurs in a special way. If structural validation fails, no other validation will occur. But once the structural validation happens, Semantic Validation and Custom Validation will happen.

Semantic Validation

Description Type
Operations cannot have both a body parameter and a formData parameter Error
Operations must have only one body parameter Error
Operations must have unique (name + in combination) parameters Error
Operations must have unique operationId Error
Path parameters declared in the path string need matching parameter definitions (Either at the path-level or the operation) Error
Path parameter declarations do not allow empty names (/path/{} is not valid) Error
Path parameters definition (Either at the path-level or the operation) need matching paramater declarations Error
Path strings must be (equivalently) different (Example: /pet/{petId} and /pet/{petId2} are equivalently the same and would generate an error) Error
Paths must have unique (name + in combination) parameters Error
Referenceable definitions should be used by being referenced in the appropriate way Warning
References must point to existing documents or document fragments Error
The default property for Schema Objects, or schema-like objects (non-body parameters), must validate against the respective JSON Schema Error
Circular composition/inheritance for Schema Objects is not allowed (You can have circular references everywhere except in composition/inheritance.) Error
The items property for Schema Objects, or schema-like objects (non-body parameters), is required when type is set to array (See swagger-api/swagger-spec/issues/174) Error
The required properties for a Schema Object must be defined in the object or one of its ancestors Error