How do I migrate a website without losing SEO traffic?

Most traffic losses after a migration come from avoidable mistakes: missing redirects, content removed or rewritten without a plan, noindex tags copied from staging, or robots.txt blocking the new site.

1. Benchmark: export rankings, top pages by traffic and conversions, and the backlinks pointing to each URL.
2. Map: crawl the old site and build a complete URL map, including images and PDFs that earn traffic or links.
3. Keep what works: titles, headings, body content and internal links on pages that perform, unless there's a reason to change them.
4. Test on staging: redirects, canonicals, hreflang, structured data, speed and rendering. Keep staging out of the index, and remove that block at launch.
5. Launch and verify: submit new sitemaps, watch Search Console for errors, and use its Change of Address tool if the domain changes.
6. Monitor for several weeks, fix issues quickly and keep redirects in place for at least a year.

Google's site move guide says to expect temporary fluctuation in rankings, and that it can take a few weeks or more for Google to show the new URLs, longer on large sites. A well-run migration aims for full SEO preservation, but it can't guarantee that nothing moves.