OpenAPI Viewer Online
Open an OpenAPI 3.0, 3.1 or Swagger 2.0 spec, YAML or JSON, to browse every operation by tag: parameters, request body, responses and schemas with $ref resolved. A short lint lists missing operationIds, unresolved $refs and path parameter mistakes. No account and no upload.
Swagger Editor & OpenAPI Editing for VS Code and Cursor, free
- Lint you can read, with quick fixes, as you edit OpenAPI 3.1, 3.0 and Swagger 2.0 in YAML or JSON.
- A live Swagger UI preview that follows your cursor, and Try it out that sends a request only when you click Send.
- IntelliSense, $ref navigation and rename, convert and bundle. No account and no telemetry.
Optional Zovo Pro, USD 19 once: a breaking-change report, a mock server and client code for any operation. 3 free tries for each.
Drop an OpenAPI or Swagger file here
or
OpenAPI 3.0 and 3.1 and Swagger 2.0, in YAML or JSON, up to 50 MB. $refs inside the file are resolved; refs to other files are listed.
Open this in VS Code or Cursor
The free Swagger Editor & OpenAPI extension edits OpenAPI 3.1, 3.0 and Swagger 2.0 files in VS Code and Cursor, with lint you can read, quick fixes, IntelliSense, $ref navigation and rename, and a live Swagger UI preview that follows your cursor. Convert and bundle are free too.
Free, MIT license. About Swagger Editor & OpenAPI for VS Code.
Zovo Pro
Breaking-change report, mock server and client code. Zovo Pro, USD 19 once.
In the Swagger Editor & OpenAPI extension, Zovo Pro compares the spec with a git ref or another file and lists every change that can break a client, serves the example responses as a mock server on 127.0.0.1, and copies a ready request for an operation in curl, JavaScript, Python, Go, Java, C# and more. Each Pro tool works 3 times for free. One payment covers the Pro tools in 22 Zovo extensions. Everything that is free stays free.
After a card payment you get a key on the page. With GitHub Sponsors you sign in from the extension. Details on the Zovo Pro page.
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Questions
Is my spec uploaded anywhere?
No. The page reads the file inside this tab. Its Content Security Policy sets connect-src to none, so the page cannot send your spec anywhere. The YAML reader (js-yaml) loads once from cdn.jsdelivr.net at a pinned version, and its hash is checked before it runs; your file is never sent there. The page makes no request when a spec opens.
Which specs does it read?
OpenAPI 3.0 and 3.1 and Swagger 2.0, in YAML or JSON, with webhooks, callbacks, security schemes, servers and tags. YAML anchors and aliases work. A file with no openapi or swagger field, such as AsyncAPI, gets a clear message.
What does it show for an operation?
The method and path, summary, description, operationId, tags, security and deprecation, then every parameter with where it goes, whether it is required and its type, the request body for each media type, and each response with its schema as a table of properties. $ref to schemas, parameters and responses inside the file are resolved, and circular schemas stop at the repeat.
What does the lint check?
That info has a title and version, servers are listed, every operation has a unique operationId, a summary or description and a success response, path parameters match the path template, every $ref inside the file points to something, and component schemas are used. It is a short readable check, not a full ruleset; the Swagger Editor & OpenAPI extension for VS Code lints as you type, with quick fixes.
Can I try the API from here?
No. This page never sends a request, so it cannot call your API. The free Swagger Editor & OpenAPI extension has a Swagger UI preview with Try it out, which sends a request only when you click Send.
Is a hostile spec safe to open?
Descriptions are shown as plain text, never as HTML or Markdown, and nothing in the spec runs. js-yaml builds plain data only. Only http and https links are clickable. Shared YAML aliases, such as a billion laughs file, are walked once, so they cannot freeze the tab, and refs to other files or URLs are never fetched.
Does it work offline?
Yes. After the first visit the page keeps a copy of its own files and of the pinned YAML reader, so it opens specs with no connection.
What is free and what is Zovo Pro?
Everything on this page is free. In the VS Code extension, editing, lint, quick fixes, IntelliSense, $ref navigation, the preview, Try it out, convert and bundle are free too. The breaking-change report, the mock server and client code are Zovo Pro, with 3 free tries each. One USD 19 payment covers the Pro tools in every Zovo extension.