OpenAPI Viewer: Explore & Validate API Specs Online
An OpenAPI viewer turns a raw spec file into a browsable API reference: paste an OpenAPI 3.x or Swagger 2.0 document (JSON or YAML) and see every endpoint grouped by tag with methods, parameters, and response codes, plus servers, schemas, and security schemes at a glance. Structural validation runs at the same time, catching missing required fields, duplicate operationIds, and operations without responses, with messages that say exactly what to fix.
How it works
- 1
Paste your OpenAPI/Swagger document (JSON or YAML) or upload the file.
- 2
Click View & Validate: the spec is parsed and structurally checked.
- 3
Browse endpoints grouped by tag, filter them, and fix any reported errors or warnings.
Frequently asked questions
How do I view an OpenAPI spec online?
Paste the document above (JSON and YAML both work) and click View & Validate. Endpoints are listed with color-coded method badges, grouped by tag, with parameter counts and response codes; a filter box narrows large APIs instantly.
What's the difference between OpenAPI and Swagger?
Swagger 2.0 is the older name and format; OpenAPI 3.x is its successor under the OpenAPI Initiative (servers replace host/basePath, requestBody replaces body parameters, components replace definitions). This viewer reads both.
What does the validation check?
Structural correctness: the version field, required info.title and info.version, a paths object, at least one response per operation, unique operationIds, and paths starting with '/'. Warnings flag missing servers and missing operationIds. It's a fast sanity check, not a full JSON-Schema audit of every sub-object.
Why do code generators fail on my spec?
The two most common causes are exactly what this tool flags: duplicate or missing operationIds (generators derive method names from them) and operations with no responses object. Fix those and most generator errors disappear.
Is my API spec uploaded anywhere?
No. Parsing and validation happen entirely in your browser, so the document never leaves your machine.
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