URL parameter variations with duplicate content are handled

Sort, filter, and UTM parameters multiply a single product listing into hundreds of crawlable URLs serving the same content. Link equity splits across every variant, so no single URL accumulates enough authority to rank. UTM parameters used inside internal <Link> components are especially toxic: they contaminate the canonical URL set and pollute analytics with self-referral traffic that looks like external campaigns.

Set a canonical in the route's metadata that always points to the parameter-free base URL, regardless of the active query string. Audit every internal <Link> and remove UTM parameters — those belong in external campaigns only. Use robots.txt to Disallow parameterized paths only when the variants genuinely have no search value.

// app/products/page.tsx
export const metadata = { alternates: { canonical: 'https://yoursite.com/products' } }