Do I need to use rel="canonical" on pages with no external links?

[Netrepid]

I know having rel="canonical" for each page on my website is not a bad practice... but how necessary is it for pages that don't have any external links pointing to them?

I have my own opinions on this, to be fair - but I'd love to get a consensus before I start trying to customize which URLs have/don't have it included.

Thank you.

[anthonydnelson]

The canonical tag is unnecessary if you don't have problems with URL variations (tracking parameters, session ids, etc). Don't just think about external links though, if your own CMS or internal linking structure links to the same pages in different ways, the canonical tag can be a patch while you work on a development fix.

All that being said, I'm a fan of having it on every page.

[SorinaDascalu]

The rel="canonical" was introduced to avoid duplicate content issues. It has nothing to do with links, internal or external.
 You use rel="canonical" to tell search engines which version of a page you prefer to be indexed.

If you prefer to tell nothing, or if there is no way a page may get indexed with a different URL then you don't need to use rel="canonical".

You are saying that your page has no external links pointing to it - but how can you control that? I may find your page, like it and link to it! This is how backlinks are supposed to work.

As you probably know each url can we written in different ways and still point to the same content. What if you prefer your page to be indexed as http://www.yourdomain.com/yourpage and I instead link to http://www.yourdomain.com/yourpage/ (note the ending /)? In these cases using rel="canonical" may help not losing any link juice.

I hope this helps.

[TakeshiYoung]

It's best practice to put canonicals on every page of your site, so that Google never gets confused by things like URL parameters. This can usually be automated by most modern CMSs.

[CleverPhD]

This is also advised as a part of the on page optimization within the Moz grading system

"Although the canonical URL tag is generally thought of as a way to solve duplicate content problems, it can be extremely wise to use it on every (unique) page of a site to help prevent any query strings, session IDs, scraped versions, licensing deals or future developments to potentially create a secondary version and pull link juice or other metrics away from the original. We believe the canonical URL tag is a best practice to help prevent future problems, even if nothing is specifically duplicate/problematic today."