axle-vercel-plugin

Run the axle accessibility scanner against every Vercel deploy preview. Fails the build when WCAG 2.1 / 2.2 AA violations cross your threshold.

Install

Set your Vercel project's Build Command (Project Settings → General → Build & Development Settings):

next build && npx -y axle-vercel-plugin

Or add it as a postbuild hook in package.json:

{
  "scripts": {
    "postbuild": "axle-vercel-plugin"
  }
}

Configuration (env vars)

Set these in Vercel → Project Settings → Environment Variables.

| Variable | Default | Notes | |----------|---------|-------| | AXLE_FAIL_ON | serious | critical / serious / moderate / minor / none | | AXLE_WITH_AI_FIXES | "false" | Set to "true" + ANTHROPIC_API_KEY for Claude-generated diffs | | AXLE_MAX_AI_FIXES | 10 | Cost guard on AI calls per build | | AXLE_URL | $VERCEL_BRANCH_URL / $VERCEL_URL | Override the target URL | | ANTHROPIC_API_KEY | — | Required only if AXLE_WITH_AI_FIXES=true |

What it does

1. Waits for your build to finish.
2. Reads VERCEL_BRANCH_URL (preferred) or VERCEL_URL — Vercel sets these automatically.
3. Invokes axle-cli scan against the preview URL.
4. Writes axle-report.json + axle-report.md into the project root so they're viewable in the deployment.
5. Prints the first ~4kB of the markdown report into build logs.
6. Exits non-zero when violations meet or exceed AXLE_FAIL_ON — this fails the deployment.

Not a compliance certificate

Remediation assistance only. Automated tools catch ~57% of WCAG issues — manual human review is still recommended.

Learn more: axle-iota.vercel.app · GitHub