URL Contains Uppercase

What "URL contains uppercase" actually means

The check flags any URL whose path or query string contains capital letters, for example https://example.com/Blog/My-Post. This matters because of a rule that trips up a lot of people: the domain part of a URL is case insensitive, but everything after it usually is not. Example.com and example.com resolve to the same host. But /Blog and /blog are two distinct paths as far as most web servers are concerned.

On a typical Linux and Apache or Nginx stack, the filesystem is case sensitive, so the server genuinely serves those as separate resources. On Windows and IIS the filesystem is not case sensitive, so both may resolve to the same file, which is arguably worse because now you have two live addresses returning identical content with no error to warn you. Either way, search engines see two URLs, and that is the problem.

Why it hurts SEO

The damage is not that uppercase is "ugly." It is that mixed case quietly manufactures duplicates. When one page is reachable at several casings, a few concrete things go wrong:

• Duplicate content. Googlebot can index /Product and /product as separate URLs holding the same content, forcing it to pick a canonical and possibly picking the wrong one.
• Split link equity. If some sites link to the capitalized version and others to lowercase, your inbound authority is divided across two URLs instead of concentrated on one.
• Wasted crawl budget. Crawlers spend requests fetching case variants of pages they already have, which on a large site means slower discovery of genuinely new content.
• Broken analytics and reporting. Your traffic for a single page gets scattered across multiple path rows, so no report tells the true story.

How case fragmentation happens

How to detect it

You want to find both the URLs on your own site that use uppercase and any inbound or internal links that point at capitalized paths.

• Screaming Frog: crawl the site, then use the built in "URL" tab filter for "Uppercase" to list every offending address in one view.
• Sitebulb: its URL hints flag mixed case paths and group them so you can see the scale quickly.
• Google Search Console: check the Pages report and the URL Inspection tool. If you see near identical paths differing only by case, that is your smoking gun.
• Server logs: grep the access logs for requests containing uppercase in the path. Real crawler hits on capitalized URLs prove the duplicates are being fetched, not just theoretical.

How to fix it, step by step

1. Decide the canonical form. Lowercase for the entire path. This is the near universal convention and the least surprising choice.
2. Add a server rule that lowercases and 301 redirects. On Apache use a RewriteMap with an internal lowercase function; on Nginx a small map plus a rewrite; on a CDN like Cloudflare a transform rule works well. The redirect must be 301 permanent so authority passes and engines update their index.
3. Fix internal links at the source. Redirects are a safety net, not the cure. Update templates, navigation, and content so your own links already point at lowercase URLs. Every internal link that fires a redirect is a small tax on crawl and speed.
4. Set self referencing canonical tags on the lowercase version so any stray uppercase request still declares the correct canonical.
5. Reclaim external links where it is worth it. For high value backlinks pointing at capitalized URLs, the 301 handles equity, but a polite outreach to correct the link is cleaner.
6. Watch for edge cases. Query string parameters, encoded characters, and tracking tags can reintroduce case sensitivity. Test with real URLs, not just the homepage.

Do vs Don't

Case handling by server

What "good" looks like

Every public URL on the site is lowercase. Requesting any uppercase variant returns a single 301 straight to the lowercase target with no chain. Internal links already use lowercase, so redirects almost never fire from your own navigation. Search Console shows one indexed URL per page, analytics reports one row per page, and your logs show crawlers fetching the canonical form and nothing else.

FAQ