https://example.com and https://www.example.com look like the same website to anyone who visits either one. To a search engine, they're two distinct URLs that happen to serve identical content, which is exactly the kind of duplication that splits ranking signals instead of consolidating them. The fix isn't picking the "right" one, there isn't one, it's making sure only one is actually reachable.
Neither Version Is Better for SEO
This gets debated more than it deserves. The old argument for www was that it let you set cookies on a separate subdomain, keeping your bare domain cookie-free for CDN caching efficiency, a real but fairly niche performance consideration that matters far less on modern infrastructure than it once did. There's no ranking preference either way from Google. Pick based on brand preference, what's already in your existing backlinks and citations, or simply what you set up first, then stop relitigating it.
What Actually Costs You
The problem isn't which form you choose. It's leaving both forms live and crawlable at once, without one redirecting to the other. When that happens:
- Backlinks pointing to
www.example.comand links pointing toexample.combuild authority for two separate URLs in search engines' eyes, instead of consolidating onto one. - Both versions can get indexed independently, showing up as near-duplicate results competing against each other rather than your site competing against everyone else's.
- Analytics and rank tracking can quietly split traffic and ranking data across two properties, understating your actual performance on either one.
The Fix Is a Redirect, Not Just a Canonical Tag
A canonical tag is a hint search engines can choose to override. For host-level duplication like this, that's the wrong tool for the actual fix, a 301 redirect at the server or DNS level, forcing every request for the non-preferred version straight to the preferred one before a page even loads. A canonical tag on top of that redirect is reasonable belt-and-suspenders; a canonical tag instead of the redirect leaves both URLs technically reachable, which is the exact problem it's meant to solve.
How to Check
Type all four combinations into a browser and watch where each one lands. If any of them return a 200 OK on their own rather than redirecting, that's the gap. Checking by hand catches the obvious cases; what it tends to miss is a redirect that exists but points to the wrong final form, or one that applies to the homepage but not to deeper URLs.
The Fast Way to Check Yours
AuditCrow's free scan checks canonicalization and redirect behaviour as part of its technical SEO review, alongside the fuller set of fundamentals in our technical SEO checklist.