Why URLs Should Be Lowercase

To a person, /About-Us and /about-us look like the same page. To many web servers, they are completely different addresses.

Servers can be case-sensitive

• Linux servers, which host a large share of websites (including typical Apache and Nginx setups), usually treat paths as case-sensitive.
• Windows servers generally treat paths as case-insensitive.

On a case-sensitive server, a link to /About-Us fails with a 404 error if the actual file is about-us.

The duplicate content problem

If your server responds to both versions with the same content, search engines may see two URLs for one page. That can split link signals and lead to the wrong version appearing in search results. Canonical tags help, but consistent lowercase URLs avoid the problem from the start.

Real-world sources of mixed case

• Slugs created from titles without lowercasing.
• Typos in internal links.
• Marketing campaigns that use capitals for readability: /SummerSale.
• Files uploaded from Windows computers with capitalized names.

How to prevent it

1. Create lowercase slugs from the start. The slug generator lowercases by default.
2. Use lowercase file names for images, PDFs and other uploads.
3. Audit internal links with a site crawler and fix mixed-case links.
4. Redirect uppercase variants to lowercase where your server allows it.
5. Set canonical tags to the lowercase version.

The domain is not affected

Domain names are always case-insensitive, so Example.com and example.com are the same. The issue applies only to the part after the domain.

Frequently asked questions

Should URLs be lowercase?

Should URLs be lowercase? Yes. Case sensitive URLs on many servers mean /Page and /page can be different pages. Mixed case URLs cause broken links and duplicate URLs.

What is a lowercase redirect?

A lowercase redirect sends any uppercase version of a URL to the lowercase one with a 301. It is part of URL normalization, which makes every page reachable at exactly one address.