API Validator

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What API Validator is

API Validator is a free browser tool for checking API descriptions against a Spectral-powered governance ruleset. It supports OpenAPI, AsyncAPI, Arazzo, and JSON Schema, with built-in Spectral rulesets for OpenAPI and AsyncAPI and curated inline rules for the other two formats. Users can upload a file or search GitHub, GitLab, and Bitbucket using their own tokens. The Monaco editor supports YAML and JSON, and rule controls let users adjust findings or disable rules; saved overrides persist in the browser. The tool can generate documentation for an artifact and download it as HTML or Markdown. Utilities include bundling $refs, componentizing, splitting artifacts by tag, channel, or workflow, and migrating JSON Schema drafts. Documents autosave to browser local storage and can be assembled into an APIs.json 0.21 index, committed to a repository, or submitted as a pull request. The maker says there are no accounts or backend and that documents and tokens stay in the browser; Git-host requests go directly from the browser when used. The whole app can be downloaded as a self-contained file for offline use. Its stated scope is deliberately limited to four artifact types.

Who it suits

It suits people who want a focused browser-based validator for the four supported artifact types. Teams seeking help can contact API Evangelist for expert governance services.

What it does well

Free and open source under Apache-2.0.
Supports four API artifact types.
Can generate HTML or Markdown documentation.
Supports repository commits and pull requests.
The app can be downloaded for offline use.

What to know first

Its scope is limited to four artifact types.
It has no CI/CD integration.
Git-host searches require users' own tokens.

Limits

API Validator is limited to OpenAPI, AsyncAPI, Arazzo, and JSON Schema artifacts. The product has no CI/CD integration.

Getting started

Open https://validator.apicommons.org/.
Upload an artifact or search GitHub, GitLab, or Bitbucket using your own token.
Use the editor to view or change the artifact in YAML or JSON.
Adjust the rules or findings for your governance needs.
Download documentation or assemble and submit the artifact changes.
Use Run Locally to download the app for offline use.

Verdict

API Validator offers browser-based linting, editing, documentation, and repository workflows for its supported formats. Its narrow scope and lack of CI/CD integration are worth considering for broader governance needs.

Questions

Is API Validator free?

Yes. It is free to use, and the project is open source under the Apache-2.0 license.

Which formats does it support?

It supports OpenAPI, AsyncAPI, Arazzo, and JSON Schema.

Can I use it offline?

Yes. The complete app can be downloaded as a self-contained file for local offline use.

Does it connect to Git hosting services?

It can search GitHub, GitLab, and Bitbucket using your own token, and can commit changes or open a pull request.

Who maintains API Validator?

It is a project of API Evangelist and is maintained under API Commons.

Facts from API Validator's own pages

Artifact search: Users can search GitHub, GitLab, and Bitbucket for artifacts using their own tokens, or upload a file from disk. · validator.apicommons.org, 7 Oct 2026
Documentation: The tool can generate documentation for the current artifact and download it as HTML or Markdown. · validator.apicommons.org, 7 Oct 2026
Editing: The editor uses Monaco and supports switching between YAML and JSON. · validator.apicommons.org, 7 Oct 2026
Git integrations: It can search GitHub, GitLab, and Bitbucket using the user's own token and can commit changes or open a pull request to a repository. · validator.apicommons.org, 7 Oct 2026
Headquarters: San Francisco, CA · validator.apicommons.org, 28 Sept 2026
Intended audience: The maker describes it as a simple, deliberately narrow validator for four API artifact types. · github.com, 7 Oct 2026
License: The repository states that the code is licensed under Apache-2.0. · github.com, 7 Oct 2026
Limits: The maker describes its scope as deliberately limited to four artifact types. · validator.apicommons.org, 7 Oct 2026
Lint engine: It uses the Spectral engine, with built-in Spectral rulesets for OpenAPI and AsyncAPI and curated inline rules for Arazzo and JSON Schema. · validator.apicommons.org, 7 Oct 2026
Local storage: Documents, tokens, saved artifacts, and rule overrides are stored in browser local storage; Git-host requests are sent directly from the browser when those features are used. · github.com, 7 Oct 2026
Local use: The Run Locally button downloads the whole app as a self-contained file that can run offline. · validator.apicommons.org, 7 Oct 2026
Maintainer: The project is maintained openly under API Commons and is a project of API Evangelist. · github.com, 7 Oct 2026
Maker: API Validator is a project of API Evangelist and is maintained under API Commons. · validator.apicommons.org, 7 Oct 2026
Offline use: The entire app can be downloaded as a single self-contained file for local use. · validator.apicommons.org, 7 Oct 2026
Pricing and licensing: The project is open source and free to fork; API Evangelist offers expert governance services for users who want help. · validator.apicommons.org, 7 Oct 2026
Privacy: The maker says the app has no backend or accounts and that tokens and documents stay in the browser. · validator.apicommons.org, 7 Oct 2026
Purpose: API Validator lints API descriptions against a Spectral-powered governance ruleset in the browser. · validator.apicommons.org, 7 Oct 2026
Rule controls: Users can filter, disable, or retune rules; saved overrides persist in the browser. · validator.apicommons.org, 7 Oct 2026
Rules: Users can adjust a finding’s severity, message, or description, or disable its rule; saved overrides persist in the browser. · validator.apicommons.org, 7 Oct 2026
Save and publish: Documents autosave to browser local storage, can be assembled into an APIs.json 0.21 index, and can be committed or submitted as a pull request to a repository. · validator.apicommons.org, 7 Oct 2026
Support: The project says API Evangelist offers expert governance services for teams seeking help. · github.com, 7 Oct 2026
Supported formats: It supports OpenAPI, AsyncAPI, Arazzo, and JSON Schema. · validator.apicommons.org, 7 Oct 2026
Transformations: Utilities include bundling $refs, componentizing, splitting by tag, channel, or workflow, and migrating JSON Schema drafts. · validator.apicommons.org, 7 Oct 2026

Where API Validator stands on Freedom251

API Governance Software#13 of 25