Should URLs be lowercase?

Yes. Use lowercase letters in your URLs. The path part of a web address is case-sensitive on many servers, so /About and /about can be different pages or one page and one error. Lowercase avoids duplicates and broken links, and it is easier for people to type and remember.

Why it matters

The host name, such as example.com, is not case-sensitive. The path after it can be. On Linux servers, /Contact-Us and /contact-us are normally different addresses, while Windows servers often treat them as the same. Google treats URLs as case-sensitive, so a site that answers on both forms has created two copies of the page, which splits links and confuses reports.

How to apply it

Write all new URLs in lowercase and separate words with hyphens, as in /blue-widgets/ rather than /Blue_Widgets/.
Set the lowercase form as the canonical version in the tag on each page:

<link rel="canonical" href="https://example.com/blue-widgets/">

Test what happens with an uppercase variant:

curl -sI https://example.com/Blue-Widgets/

You want either a 404 or a 301 redirect to the lowercase address, not a second page with a 200 status. 4. If your server answers both, add a redirect rule that lowercases the path. In nginx this usually needs a small map or a Lua or njs module, and in Apache it needs a RewriteMap defined in the main server configuration. Many CMS tools and frameworks have a "lowercase URLs" setting, which is easier. 5. Make sure internal links, the sitemap and canonical tags all use the lowercase form. 6. Keep existing uppercase URLs only if renaming them would break many outside links. In that case leave them, canonicalize carefully and redirect any other case variant. 7. Watch the Page indexing report in Search Console for duplicates that differ only in case.

Common mistakes

Redirecting some case variants but not others.
Lowercasing the query string, which may contain case-sensitive values.
Changing existing URLs without redirects from the old case.
Using uppercase file names for images and scripts, then linking to them in lowercase.
Mixing case in links written by different people.

Frequently asked questions

Does uppercase hurt rankings?

Not directly. The problem is accidental duplicates and broken links, which lowercase URLs prevent.

Is the domain name case-sensitive?

No. Browsers treat Example.com and example.com as the same host, and only the path and query string may differ.

Should I change old uppercase URLs?

Only if you can redirect each one to its lowercase version with a 301 redirect. If the change is risky, keep them and focus on consistency in new content.

To check how your site's addresses behave, Try the free website sample.