A website migration can combine design, platform, content and URL changes in one project. That makes it easy for useful pages to disappear or important routes to break. SEO planning should therefore begin before launch rather than as a clean-up exercise afterwards.
Record the existing URL set before changing it
Create a reliable inventory of current pages and identify which ones have a continuing purpose. This provides the baseline for decisions about keeping, replacing, consolidating or retiring URLs instead of discovering omissions after the new site is live.
Map old destinations to genuinely relevant new ones
Where URLs change, redirects should lead users to the closest useful replacement. Sending every removed page to the homepage hides information loss rather than solving it. If no meaningful replacement exists, make an explicit retirement decision.
Protect important content during redesign
Visual improvements can accidentally remove explanations, service detail and internal links that made an old page useful. Compare old and new versions by purpose and information, not merely appearance, so the redesign does not reduce the substance readers rely on.
Check navigation and internal links on the new structure
Confirm that important pages can be reached through sensible site routes and that old internal URLs have been updated. A redirect may rescue a broken link, but correcting the source link creates a cleaner long-term structure.
Test the technical basics before launch
Review indexability, canonical handling, status responses and other essential controls in the environment available to the project. The exact checks depend on the platform and migration scope, so use evidence from the actual build rather than a generic checklist alone.
Monitor the migration as a change, not a single event
After launch, inspect the new site for unexpected missing pages, redirect problems and changes affecting priority areas. Keep the original inventory and mapping available so issues can be traced back to migration decisions rather than investigated without context.