Free Online OpenAPI Viewer

An OpenAPI viewer lets you turn a raw OpenAPI or Swagger YAML/JSON document into a readable, interactive page — endpoints, parameters, request/response schemas, and a "Try it out" button to call real endpoints, without installing anything or hosting your own Swagger UI instance.

SpecViewer is a free, browser-based OpenAPI viewer: paste your spec, import a file, or load a public URL, and it renders instantly using Swagger UI — entirely client-side, with nothing uploaded to a server.

How to view an OpenAPI spec online

1. Open specviewer.app.
2. Click + Add Spec in the sidebar.
3. Paste your OpenAPI/Swagger YAML, or import a .yaml/.yml file.
4. Hit Save — your spec renders immediately, ready to browse or call live with Try It Out.

Why use a browser-based viewer

• No install, no account, no backend — just a browser tab.
• Specs are saved to your browser's localStorage, so they persist across sessions without leaving your device.
• Manage multiple specs at once, organized into folders, and switch between them instantly.
• Visually compare two versions of a spec to catch breaking changes before a release.