Subdomain or subfolder for a knowledge hub?

Use a subfolder when the hub is part of the same offering as the main site, which is most of the time. Use a subdomain when the hub is a separate surface with its own stack, brand or language estate. Both work; changing your mind later is the expensive option.

This argument has been running for fifteen years and generates more heat than the difference deserves. Both are indexed. Both can rank. The real considerations are less about authority than the debate suggests.

The case for a subfolder

• One domain to build, one to maintain, one set of signals accumulating in one place.
• Internal linking between the hub and the commercial pages is ordinary linking, not cross-domain linking.
• One analytics property, one consent configuration, one set of security headers.
• Nobody has to decide which property a page belongs to, which is a surprisingly persistent source of internal argument.

The case for a subdomain

• The hub runs on different infrastructure from the main site, and putting it in a subfolder means a reverse proxy somebody has to own.
• The main site is on a platform you cannot add sections to without an agency and a quote.
• The hub is a genuinely separate surface: a support centre, a developer portal, a product used by people who are not buyers.
• You run separate language estates and want them to be independently manageable.

The third and fourth of those are the good reasons. The first two are practical reasons, which are also legitimate — a hub that ships on a subdomain this quarter is worth more than a subfolder that is still being negotiated next year.

A hub that ships beats a hub that is architecturally perfect and unbuilt.

What actually matters more than the choice