SpecViewer — Free Online OpenAPI & Swagger Viewer

Paste or import your OpenAPI / Swagger YAML spec and instantly view, test, and compare API endpoints in your browser. No signup, no backend, nothing leaves your device. SpecViewer is the new home of SwagView.

Paste YAML instantly — drop OpenAPI or Swagger YAML directly into the editor.
Import files or URLs — load .yaml/.yml files or bulk-import from public URLs.
Compare specs visually — diff two OpenAPI documents side-by-side.
Try It Out — call real endpoints directly from the viewer.
Local-only storage — every spec stays in your browser's localStorage.

+ Add your first spec

Frequently asked questions

What is SpecViewer?

SpecViewer (formerly SwagView) is a free, browser-based tool for exploring OpenAPI and Swagger specifications. Paste YAML, import files, or load public URLs to instantly view, test, and compare API endpoints — no signup, no backend, nothing leaves your device.

Is SpecViewer free?

Yes. SpecViewer is completely free to use, with no account or signup required.

Does SpecViewer store or upload my API spec?

No. Every spec you add is saved locally in your browser's localStorage. Nothing is uploaded to a server.

Can I compare two OpenAPI or Swagger specs?

Yes. SpecViewer includes a visual diff tool that highlights added, removed, and changed paths, parameters, and schemas between two specs — useful for catching breaking changes before a release.

What's the difference between OpenAPI and Swagger?

Swagger was the original specification and tooling for describing REST APIs. It was donated to the Linux Foundation and renamed OpenAPI, which is now the current standard. In practice the terms are often used interchangeably, and SpecViewer supports both OpenAPI 3.x and Swagger 2.0 documents.

SpecViewer

Explore and visualize your OpenAPI specs in one place.

Trusted by 300+ developers in 12 countries

Paste YAML

Paste your OpenAPI YAML directly into the editor

Import File

Load a .yaml or .yml file from your machine

Auto Saved

All specs are stored locally in your browser

Try it Out

Interact with endpoints directly from the viewer

Live Edit

Edit specs live and see changes in real-time

get started

Runs in your browser
No signup
Free

No spec selected

SpecViewer

Paste YAML

Import File

Auto Saved

Try it Out

Live Edit

Edit YAML

Add Spec

Import Multiple Specs

Share Spec via Link