Free tool OpenAPI 3.0 OpenAPI 3.1 OpenAPI 3.2

Free Online OpenAPI 3.2, 3.1 & Swagger Validator

Validate OpenAPI 3.2, 3.1, 3.0 & Swagger 2.0 specifications. Paste JSON/YAML, upload files, or fetch from URL.

Specification 

1
No input ·

Documentation Preview

Paste or upload your OpenAPI spec and click Validate to see a live preview.

Formats
JSON / YAML
Versions
2.0 / 3.x
Cost
Free
CI/CDGitHub Marketplace Action

Automate OpenAPI validation and diff checks on every PR.

When your spec is valid here, enforce the same checks in CI with our GitHub Action. Detect breaking changes, post a single PR summary comment, and block bad merges.

Supports OpenAPI 3.0, 3.1, 3.2 and Swagger 2.0
Public repos: free and unlimited, no API key required
Fast JavaScript action, no Docker image required
Install from GitHub Marketplace See full setup guide

Public repository

- uses: apinotes/openapi-validate@v1
  with:
    spec-path: 'openapi.yaml'

Private repository

- uses: apinotes/openapi-validate@v1
  with:
    api-key: ${{ secrets.APINOTES_API_KEY }}
    spec-path: 'openapi.yaml'

Recommended branch protection setup

Enable Require status checks to pass before merging and select your validate job to block invalid or breaking spec changes.

Why validate your OpenAPI Specification?

Ensuring your API specification validates against the official standard is crucial for generating accurate documentation and SDKs.

Syntax Errors

Invalid JSON or YAML formatting

Schema Compliance

Adherence to OAS 3.0, 3.1 or 3.2

Missing Fields

Required properties checks

🆕

OpenAPI 3.2

Latest release, fully supported

🚀

OpenAPI 3.1

Latest standard with webhooks

📚

Swagger 2.0 & OAS 3.0

Full backward compatibility

How to use this validator?

Four simple steps to validate your OpenAPI specification.

1

Paste or Upload

Copy your OpenAPI JSON/YAML content or upload a file directly.

2

Instant Feedback

Our validator parses your spec against official schemas in real-time.

3

Fix & Retry

View detailed error messages to quickly resolve issues.

4

Preview & Publish

Once valid, preview your documentation and publish it instantly.