How to Fix Duplicate Content (Canonical, 301, noindex)

Duplicate content is when the same or very similar content is available at multiple URLs. It confuses search engines about which version to rank and splits your ranking signals.

Common Causes

• http:// and https:// versions both accessible.
• www and non-www versions.
• URL parameters (?ref=, ?sort=) creating duplicate pages.
• Printer-friendly or AMP versions.
• The same product in multiple categories.

The Three Fixes

1. Canonical Tag (most common)

Tells Google which version is the "master" to index. Keep all versions accessible but point them to one canonical:

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

Use when: pages are similar but you want all accessible (e.g., parameter variations).

2. 301 Redirect

Permanently sends users and search engines to the canonical URL. The duplicate stops existing.

Use when: you want to fully merge two URLs (e.g., http→https, www→non-www).

# Nginx: force https + non-www
return 301 https://example.com$request_uri;

3. noindex

Keeps the page accessible but out of search results.

Use when: a page must exist for users but should never rank (e.g., internal search results).

<meta name="robots" content="noindex,follow">

Quick Decision Guide

Find Duplicates

Run your URL through SEO Snapshot — it checks your canonical tags and HTTPS/redirect setup to surface duplicate-content risks.