How do I install Aether WCAG Scanner?

Copy the stdio config for Cursor, Claude Desktop, Claude Code, or VS Code on this page. It uses the publisher's install, not a PlugMCP proxy.

Does Aether WCAG Scanner need an API key?

The publisher lists these environment variables: ALLCHEMY_API_KEY.

What transport does Aether WCAG Scanner use?

Aether WCAG Scanner runs locally over stdio.

When was Aether WCAG Scanner last checked?

Last checked 2026-11-09. WCAG 2.1 AA accessibility scanner (Playwright + axe-core) with grounded, browser-verified fixes.

Aether WCAG Scanner MCP server

Power your agent

Add this server

The publisher's own command. Not a PlugMCP endpoint.

Add to Cursor Add to VS Code Run on PlugMCP

Host a copy with our keys and logs.

Local command

npx -y @allchemylabs/[email protected]

Credentials from the publisher

ALLCHEMY_API_KEY — Beta API key from https://beta.allchemylabs.ai/?src=registry (optional: without it the scanner runs fully offline with template fixes)

Claude Code has no install link for a local command. Copy the command below and run it in a terminal.

shClaude Code

1ALLCHEMY_API_KEY=<secret> claude mcp add io.github.allchemylabs-aether-wcag-scanner -- npx -y @allchemylabs/aether-wcag-scanner@1.0.8

Run in a terminal.

jsonClaude Desktop

1{2  "mcpServers": {3    "io.github.allchemylabs-aether-wcag-scanner": {4      "command": "npx",5      "args": [6        "-y",7        "@allchemylabs/[email protected]"8      ],9      "env": {10        "ALLCHEMY_API_KEY": "<secret>"11      }12    }13  }14}

claude_desktop_config.json

Local · npmPublisher installStep-by-step: add this in Claude

Remote URL or a command on your machine? How the two installs differ

Run on PlugMCP

Host a copy with our keys and logs.

A new server you create. It is not this listing's official endpoint. Use the publisher install when you want their URL and their credentials.

Launch

Server facts

Local

Transport: stdio
Version: 1.0.8
API key

Tools

No tool list yet. Remote servers get one after the first health check.

FAQ

Questions

Aether WCAG Scanner

An MCP server for Claude Code, Cursor, Codex and other coding agents that finds WCAG 2.1 AA accessibility violations and returns ready-to-apply fixes — not just a list of problems.

It drives a real browser (Playwright + axe-core) across desktop, tablet, and mobile viewports, then pairs each violation with a concrete fix: corrected HTML, the relevant WCAG success criteria, and technique code examples.

It works free without a key. For higher quality, contextual fixes, get a beta key at beta.allchemylabs.ai (sign in with GitHub).

Why it's different

An AI coding agent working from markup alone has to infer what a page does. Aether runs the page in a real browser, measures it with axe-core, and grounds every suggested fix in the WCAG spec, so the agent is working from measurements rather than inference.

	Coding agent alone	Aether, offline	Aether, with API key
How it looks at the page	Reads the HTML it is given	Renders the page in Chromium at desktop, tablet and mobile widths and runs axe-core	Same
What it can measure	Structure visible in the markup	What axe measures on the rendered page: contrast, accessible names, ARIA usage, focusable regions, landmarks	Same
Fix suggestions	From the model's general knowledge	Deterministic templates for the common rules	Templates first, then WCAG-corpus examples, then a model; every cited technique passes a grounding check
How fixes are checked	Not checked unless you set that up	axe re-run on the fixed element; reports what cleared and what regressed	Same
What each fix cites	Whatever the model recalls	The axe rule and its severity	The WCAG success criteria and techniques, with rejected candidates shown
Network	Depends on the agent	None; runs entirely on your machine	Fix requests go to the hosted engine; falls back to offline templates when it is unreachable

Install

/plugin marketplace add https://github.com/allchemylabs/claude-plugins.git
/plugin install aether-wcag-scanner@allchemylabs

Once the official Claude Code marketplace listing is live, you can also install it directly from there.

Installing with /plugin install inside Claude Code prompts for your Allchemy Labs API key; paste the key you got from beta.allchemylabs.ai. Installing from the terminal (claude plugin install …), or letting Claude run the install for you, does not prompt, so set the key afterwards with the command below. Run the same command to change the key later:

/plugin configure aether-wcag-scanner@allchemylabs

The first start installs the plugin's dependencies (about a minute) and the first scan downloads Chromium for Playwright. If /mcp shows the server as not connected right after install, wait a moment and run /reload-plugins.

Running without a key

The plugin asks for a key at install because the cloud fixes need one. The scanner itself runs locally and still works without a key (for example after a terminal install, or via npx): you get local template fixes for every violation. A beta key adds higher quality, contextual fixes from the hosted insights engine; get one at beta.allchemylabs.ai (sign in with GitHub). Set it via the prompt above, or put ALLCHEMY_API_KEY=<key> in the .env of the project you are scanning.

Use it outside Claude Code (any MCP client)

The same server is published to npm and the MCP Registry as @allchemylabs/aether-wcag-scanner. Any MCP client that speaks stdio can run it:

{
  "mcpServers": {
    "aether-wcag-scanner": {
      "command": "npx",
      "args": ["-y", "@allchemylabs/aether-wcag-scanner"],
      "env": { "ALLCHEMY_API_KEY": "<your beta key>" }
    }
  }
}

The first scan downloads Playwright's Chromium once (about 500 MB on disk: the browser plus its headless shell). Without ALLCHEMY_API_KEY the scanner still runs fully offline and returns template fixes.

Claude Code gets the /wcag-scan skill, which drives the scan → review → fix → verify loop. Other agents only see the tool descriptions and the instructions the server sends at connect time, so for the same behaviour copy AGENTS.md into your project (Codex reads it natively; Cursor and Windsurf accept it as a rules file). Without it an agent may fetch the page HTML and guess instead of running the browser scan.

The 5 tools

Tool	What it does
`aether_scan_and_fix`	Recommended. Scan a URL — or a single-page app across routes via the `spa` block — and return violations with fixes, each verified on the real browser, in one call. Set `maxFixes: 0` for a fast scan-only pass.
`aether_get_fix`	Get a fix for one specific violation (verified on the real browser). Omit `html` to instead get a rule-level explanation — WCAG success criteria and technique examples.
`aether_verify_fix`	Deterministically verify a fix with real Playwright + axe — re-scan a URL or diff original vs fixed HTML. Reports whether the target cleared, any new regressions, and the net compliance delta.
`aether_check_html`	Analyze an HTML snippet for issues — no live URL or browser needed.
`aether_submit_feedback`	Rate a fix (useful / not useful) so the guidance engine keeps improving; your correction helps seed better fixes.

Just ask Claude naturally, e.g. "check localhost:3000 for accessibility issues and fix them" — it will pick the right tool.

The `/wcag-scan` skill

Run /wcag-scan <url> for a guided workflow: scan → review violations → apply fixes → re-scan to verify → summarize. The skill orchestrates the tools above and edits your files in place.

Hooks

The plugin adds two hooks to Claude Code:

Session start: checks that the plugin's dependencies and Chromium are installed, and installs them on the first run.
After each edit: when Claude edits an HTML, JSX, TSX, Vue or Svelte file, a quick heuristic check (no browser) reports possible accessibility issues to Claude. It never blocks an edit, and its findings can be false positives.

To turn the post-edit check off in every project, run /plugin configure aether-wcag-scanner@allchemylabs and set Post-edit accessibility check to false. To turn it off (or back on) for one project, add this to that project's .claude/settings.local.json:

{ "env": { "AETHER_POSTEDIT_HOOK": "0" } }

Use "1" to turn it back on for that project. Restart Claude Code after either change.

Scanning single-page apps

Pass a spa block to aether_scan_and_fix instead of url:

{ "spa": { "entryUrl": "http://localhost:4200", "framework": "angular", "maxRoutes": 10 } }

entryUrl — where the app boots. Routes are discovered by crawling client-side links unless you list them in routes: [{ "path": "/settings", "name": "Settings" }].
framework — angular, react, vue, or omit to auto-detect.
maxRoutes — cap on discovered routes.

Navigation is client-side (the browser context and app state are kept between routes), and readiness is decided by a layered stability cascade — DOM quiet, framework hooks such as Angular testability, pending-request drain — never by Playwright's networkidle, which deadlocks on apps with long-polling or websockets. A config that sets networkIdle is rejected for that reason.

Requirements

Node.js >= 20
Chromium (installed automatically on first run)

Disclaimer

Aether is an accessibility analysis and guidance tool. Using the platform does not, by itself, make your website, application, or digital service conformant with WCAG, the ADA (including Title II), the European Accessibility Act, Section 508, EN 301 549, or any other accessibility law or standard.

Automated scans detect only a subset of accessibility barriers. A "zero issues" result means the scanner did not flag anything in its detection range — not that the property is legally compliant.

You remain responsible for:

reviewing findings with qualified people
fixing issues in the underlying code and content
conducting or commissioning manual testing and audits as needed
maintaining accessibility as the product changes
obtaining legal advice for your specific obligations

Aether does not provide legal advice and does not replace an accessibility audit or a VPAT/ACR prepared by a qualified auditor.

License

MIT for the client (this plugin). The hosted insights engine and related Allchemy Labs services are proprietary — see LICENSE and NOTICE.

Add this server

Host a copy with our keys and logs.

Server facts

Tools

Questions

How do I install Aether WCAG Scanner?

Does Aether WCAG Scanner need an API key?

What transport does Aether WCAG Scanner use?

When was Aether WCAG Scanner last checked?

Documentation

Aether WCAG Scanner

Why it's different

Install

Running without a key

Use it outside Claude Code (any MCP client)

The 5 tools

The /wcag-scan skill

Hooks

Scanning single-page apps

Requirements

Disclaimer

License

The `/wcag-scan` skill