It usually means the same page is being served with more than one variation of the URL. Fathom treats unique URLs as unique pages, so if your site can be visited at both http://example.com/page and https://example.com/page, or www.example.com/page and example.com/page, you’ll see separate rows for what looks like the same pathname. Below are the most common causes, how to confirm what’s happening, and fixes we recommend.

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How to view the full URL in your dashboard

If you’re unsure which exact URL Fathom recorded, hover over the pathname in the Pages box. Your browser will show the full URL (typically in the bottom-left corner). This is the quickest way to spot differences like http vs https, www vs non-www, or a different domain/subdomain.

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Common causes and how to fix them

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1) Both www and non-www versions are accessible

Symptom: You can visit both https://example.com/page and https://www.example.com/page and they both load without redirecting. Fathom will treat these as separate pages. Fix: Choose a primary host (with or without www) and permanently redirect the other to it. Example fixes:
  • DNS + web server: Point both hosts at your server, but have the secondary host 301 redirect to the primary.
  • NGINX (force non-www): 
    server {
  listen 80;
  server_name www.example.com;
  return 301 https://example.com$request_uri;
}
server {
  listen 443 ssl;
  server_name www.example.com;
  return 301 https://example.com$request_uri;
  # ssl_certificate / ssl_certificate_key ...
}
  • Apache (.htaccess, force www to non-www): 
    RewriteEngine On
RewriteCond %{HTTP_HOST} ^www\.example\.com$ [NC]
RewriteRule ^(.*)$ https://example.com/$1 [L,R=301]
  • Cloudflare: Use a single A/AAAA record for the primary host. Add a Redirect Rule to send www.example.com/* → https://example.com/$1 (301).
Tip: Be consistent with internal links and your <link rel="canonical"> tag so everything points to your chosen host.

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2) Both http and https are accessible

Symptom: http://example.com/page and https://example.com/page both load. Each protocol shows up as a separate URL. Fix: Redirect all HTTP traffic to HTTPS, and consider enabling HSTS. Example fixes:
  • NGINX (force HTTPS): 
    server {
  listen 80;
  server_name example.com www.example.com;
  return 301 https://$host$request_uri;
}
  • Apache (.htaccess): 
    RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
  • Cloudflare: Turn on “Always Use HTTPS” and (optionally) HSTS after testing.

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3) The domain differs (localhost, staging domains, or subdomains)

Symptom: You see the same pathname under different domains, for example:
  • https://example.com/pricing (production)
  • https://staging.example.com/pricing (staging)
  • http://localhost:3000/pricing (local dev)
Fix options:
  • Block non-production domains using Allowed Domains so dev/staging traffic is never recorded.
  • If you do want subdomain data, enable Multi-domains so each domain/subdomain is clearly grouped and reported.
Recommendation: For most teams, allow only the production domain(s) and exclude localhost/staging entirely. Enable multi-domains only when you intentionally want to analyse multiple domains or subdomains under the same site.

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Canonical link doesn’t match the page URL

Fathom will default to using the page’s canonical URL if a <link rel="canonical" href="..."> tag is present. If your canonical points to a different host or path than the one the visitor is on, you’ll see data attributed to that canonical URL instead. How to check:
  1. Open the page in your browser and view source (or inspect).
  2. Find the <link rel="canonical"> tag and confirm the href exactly matches your intended, public URL (correct protocol, www vs non-www, correct domain/subdomain, correct path and trailing slash conventions).
  3. Hover over the pathname in Fathom’s Pages box to compare the recorded URL with your canonical.
Fix: Update your canonical tags to match the real, public URL you want to report on. This will also helo your site’s SEO. Alternative: If you have a unique setup and do not want Fathom to use canonical URLs, you can tell the Fathom script to ignore them. Instructions here.

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Verification checklist

  • Open each variant (http vs https, www vs non-www, subdomain vs root) and make sure every non-primary URL 301-redirects to your primary URL.
  • Check a few representative pages for a correct canonical tag that matches your chosen host and path.
  • In Fathom, hover page rows to confirm the full URL matches your expectations.
  • If you use test/staging/local environments, configure Allowed Domains (to block them) or Multi-domains (to measure them intentionally).

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FAQ

Will this merge my historical duplicates?
No. Redirects and canonical fixes prevent future duplication. Historical rows will remain as they were recorded. Do trailing slashes matter?
Yes, https://example.com/page and https://example.com/page/ are distinct URLs. Pick a convention, redirect the other, and make sure your canonical tags and internal links follow the same convention. Do query strings matter?
No. By default, Fathom strips query strings from page URLs. Only UTMs (utm_source, utm_medium, utm_campaign, utm_term, utm_content) and the ref parameter are read for attribution — and they don’t create separate page rows. So https://example.com/page?a=1 and https://example.com/page are reported as the same page. If you’re seeing duplicates, it’s almost certainly due to host/protocol differences or canonicals, not query strings.

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Still having issues?

If you’ve worked through the above and still see unexpected duplicates, contact our support team and send us a couple of example URLs (the exact URLs you see when you hover in the Pages box) and we’ll help you untangle what’s going on.