# Canonical Tag Checker for Next.js

> Paste your Next.js page HTML and verify the metadata alternates.canonical output.

Free tool: https://mars.cx/tools/canonical-url-checker-for-nextjs

Next.js metadata generates the canonical from alternates.canonical; verify it renders as expected.

## How to use

1. Paste your page HTML.
2. Review the extracted SEO tags.
3. Fix any missing or mismatched canonical.

## FAQ

### Why canonical matters?

It tells search engines which URL is the preferred version, preventing duplicate-content issues.

### Should it be absolute?

Yes, canonicals should be full absolute URLs.

### Is it free?

Yes, free with no signup.

Provided by MarsGeo — https://mars.cx