canonical_link: Definition

Submit the canonical_link attribute for products that are eligible for free product listings on Google and use it to ensure your products are associated with the correct URL in Google's Search index. The URL in this attribute is not served to users but will improve Google's understanding about the product.

The canonical_link attribute works similarly to the "canonical URL" markup tag, and allows you to influence which URLs Google uses for your products in our web search index.

If you use tracking or variant selection parameters in your link or mobile_link attributes, we recommend using the canonical_link attribute. For example, let’s say you sell couches that vary by color and size. You may submit one URL for each variant’s landing page using the link attribute. You may then use the canonical_link attribute to direct all variants of the product to the landing page of the base product, which has no variant parameters (such as size or color) pre-selected. URLs discovered by Google’s web search crawler typically link to a single base product without any pre-selected parameters.

When to use

Optional for each product

Use the canonical_link attribute to indicate which URL you’d prefer Google use when matching your products' landing pages with the Search index. If you do not indicate a canonical link, Google will crawl your site and set whichever URL it considers to be the most representative as the canonical link.

If you already provide a canonical URL in your product landing page markup you do not need to provide the canonical_link attribute. If you provide a value for both and those values don’t match, Google will select a link based on internal signals.

You can also set a noindex tag in the html of your landing page if you want to prevent your page from being crawled and added to the web index.

Format

Follow these formatting guidelines to make sure Google understands the data you're submitting.

For details on when and how to submit values in English, learn more about submitting your product data

Type	URL (including `http` or `https`), ASCII characters only, and RFC 3986 compliant
Limits	1 – 2,000 characters
Repeated field	No

File format	Example entry
Text feeds	`http://www.example.com/writing/google-pens`
XML feeds	`<g:canonical_link>http://www.example.com/writing/google-pens</g:canonical_link>`

To format your data for Content API, see the Content API for Shopping.

Guidelines

Follow these guidelines to make sure you submit high-quality data for your products.

Minimum requirements

These are the requirements you'll need to meet to show your product. If you don't follow these requirements, we'll disapprove your product and let you know on the Diagnostics page of your Merchant Center account.

Make sure that your canonical link meets the requirements for canonical URLs. Learn more about requirements for canonical URLs
Start with preferably https or http and comply with RFC 3986. For example: https://www.example.com/writing/fiji-pens.
Use your verified domain name. Make sure to use the domain name that you verified (during account setup or through the Website Verification tab). Learn more about how to verify and claim your domain name
Make sure your canonical URLs can be crawled by Google. For example, ensure your robots.txt file is configured correctly. Otherwise, your landing page will not appear in the search results. Learn more about robots.txt files
Replace any symbols or spaces with URL encoded entities. For example, if your URL contains an &, then replace it with %26.
Submit only one canonical_link attribute for your product. If you provide multiple canonical_link attributes for the same item, only one of them will be applied.

Best practices

These best practices can help you go beyond the basic requirements to optimize your product data for performance.

Use a stable canonical URL. The URL that you include shouldn’t change unless your landing page moves. Don’t use URLs with timestamps or parts that could change each time you submit your product data. Whenever you change your URL, your landing page will need to be evaluated and crawled. This process could cause unnecessary load on your servers.
Use a landing page that doesn’t include parameters in its URL as the destination for your canonical link. If parameters are set, Google may crawl the URL inefficiently and exclude the URL that you want to include.
Don’t use pre-selected variants. The canonical link to your landing page should have no pre-selected variants.
Don’t use tracking parameters in canonical links. Tracking parameters may be removed by Google’s web crawler and will make matching of your products against the search index less accurate.
Don’t use the ads_redirect attribute for your canonical links. Redirects may not be crawled by Google’s web crawler and your URL may not be included in search results.

Examples

Variants

If you have multiple URL variants of the same product, for example, a dress in multiple colors or sizes, you can set the canonical_link attribute to direct all variants of the product to a single base product, which has no variants pre-selected, as in the examples below:

Product	Dress
`color`	blue
`size`	small
`link`	https://example.com/dress/blue-small
`canonical_link`	https://example.com/dress

Product	Dress
`color`	green
`size`	small
`link`	https://example.com/dress/green-small
`canonical_link`	https://example.com/dress

Product	Dress
`color`	blue
`size`	large
`link`	https://example.com/dress/blue-large
`canonical_link`	https://example.com/dress

Product	Dress
`color`	green
`size`	large
`link`	https://example.com/dress/green-large
`canonical_link`	https://example.com/dress