WordPress

WordPress itself adds a canonical only to single posts and pages. Yoast SEO and Rank Math add it to every page (home, categories, archives) and are the simplest fix for a missing tag: install one, and the tag appears.

When the canonical points to the staging address, the old address is still stored somewhere:

1. Settings → General: WordPress Address (URL) and Site Address (URL) must both be the live address.
2. A single page can have its own canonical: Yoast SEO box → Advanced → Canonical URL, or Rank Math → Advanced → Canonical URL. Empty means "this page", which is what you want.
3. If the staging address is still in the database (posts, widgets, plugin settings), replace it everywhere. With WP-CLI, try a dry run first:

wp search-replace 'https://staging.example.com' 'https://example.com' --all-tables --dry-run
wp search-replace 'https://staging.example.com' 'https://example.com' --all-tables

Back up the database before the second command. Without WP-CLI, a search-and-replace plugin does the same. Then clear the page cache.

Node.js and Next.js

In the Next.js App Router, set metadataBase once in the root layout and the canonical in each page:

// app/layout.js
export const metadata = {
    metadataBase: new URL('https://example.com'),
};

// app/services/page.js
export const metadata = {
    alternates: { canonical: '/services/' },
};

For dynamic pages, return it from generateMetadata:

export async function generateMetadata({ params }) {
    const { slug } = await params;

    return { alternates: { canonical: `/blog/${slug}` } };
}

Do not put alternates.canonical in the root layout: every page that does not override it inherits it, and the whole site points to the home page. If the canonical shows a preview address, metadataBase is built from an environment variable that is not set for production.

Laravel

In the layout's <head>:

<link rel="canonical" href="{{ url()->current() }}">

url()->current() is the current address without the query string, so ?utm_… and ?page= variants all point to the clean address. Behind a load balancer or Cloudflare, make sure Laravel trusts the proxy, otherwise it builds http:// addresses. If you build the canonical from config('app.url'), check APP_URL in the live .env and run php artisan config:cache.

Static HTML

Add the tag to the <head> of every page, each with its own address:

<link rel="canonical" href="https://example.com/contact/">

Use the exact form the site really uses: https://, with or without www, and with or without the trailing slash, as the site redirects.

Shopify

Shopify themes print the canonical in theme.liquid. If the checklist finds none, open Online Store → Themes → … → Edit code → Layout → theme.liquid and add this inside <head>:

<link rel="canonical" href="{{ canonical_url }}">

If it points to *.myshopify.com or an old domain, set the right domain as primary under Settings → Domains.

Wix

Wix adds the canonical on its own, based on the connected domain. If it points to the wrong host, check that your domain is connected and set as the primary domain. A single page can have a custom canonical in the page's SEO settings (Advanced SEO); leave it empty unless you have a reason.

Webflow

Open Site settings → SEO and set Global canonical tag URL to your live domain, e.g. https://example.com (without a path; Webflow adds each page's path). Also check that the domain is set as the default under Site settings → Publishing, then Publish.

Squarespace

Squarespace adds the canonical on its own and it cannot be edited. It uses the primary domain: if it shows *.squarespace.com or an old domain, set the right one as primary in the Domains settings.