Multilingual website SEO: hreflang, canonicals and URL structure

One domain, one folder per language

Subfolders like /pl/ and /en/ on a single domain consolidate authority, so both languages benefit from every backlink.

Redirect secondary domains (e.g. a .pl domain) with a permanent 301 to the matching language folder.

hreflang and self-referencing canonicals

Each page should list its equivalent language versions with hreflang, including itself. Use x-default for the homepage language chooser, rather than pointing every article or case study back to the homepage.

For distinct translated pages, use a canonical URL in the same language. Canonicals help Google choose the preferred URL; hreflang connects the equivalent translations.

Suggest, don't force

Automatic redirects based on browser language can block crawlers from seeing a version. Show a polite language suggestion instead.