Website migration without losing SEO – keep your rankings when URLs change

How 301 redirects carry your SEO through a migration

A 301 redirect tells browsers and search engines that a page has moved permanently to a new address. Visitors who open the old URL land on the new page automatically, and over time Google treats the new URL as the main version. Links from other sites, bookmarks and URLs printed on business cards or flyers keep working.

A 302 redirect signals a temporary move and suits things like a maintenance page. For a migration or domain change that will not be reversed, use 301 redirects.

• Domain change: every page on the old domain points to the matching page on the new one
• URL change: pages with new folder names or slugs redirect one-to-one to their new address
• CMS migration: moving from WordPress to Shopify, for example, changes URL formats that need redirecting in bulk
• HTTPS and www: http:// redirects to https://, and the www and non-www versions are merged into one

In every case the work starts with one list: every URL you have today and where it goes after the move. That list is your redirect map.

Why rankings drop after a domain or URL change

Most post-migration drops come from avoidable setup mistakes. Knowing them in advance makes planning far easier.

• Old URLs are not redirected and return 404 errors in large numbers
• Every old URL is sent to the home page, so page-level relevance is lost
• Redirect chains (A to B to C) slow pages down and weaken the signal
• Redirects meant to be 301 are actually 302 or JavaScript-based
• Well-performing pages lose much of their text and headings on the new site
• Canonical tags and internal links on the new site still point to old URLs
• The noindex setting from the staging site is left on at launch

Some movement in rankings right after a move is normal. Without the issues above, it typically settles within a few weeks to a few months. If the design and structure are changing too, read our guide to SEO during a site renewal.

How to build a redirect map

A redirect map is a simple spreadsheet: one row per old URL, with its new URL next to it. The accuracy of this sheet matters more than the redirect setup itself.

• Collect every old URL: combine your sitemap, the Pages report in Search Console, page data from GA4 and a site crawl
• Mark what matters: flag high-traffic pages, pages with backlinks and pages that lead to inquiries or sales
• Map one-to-one: choose the new page with the closest content; merged pages go to the merged page, and pages with no match go to the most relevant category
• Decide what to retire: pages that have truly served their purpose can return 404 or 410
• Check the extras: filter URLs with parameters, PDFs and frequently linked images

Then review the new URLs for inconsistencies: trailing slashes, upper and lower case, and encoded Japanese characters. Getting internal sign-off at this stage saves rushed fixes on launch day.

Setting up redirects on different platforms

How you set redirects depends on what runs your site, so check the options when choosing where to move.

• Apache servers: rules in .htaccess, ideal for whole-domain moves and pattern-based redirects
• WordPress: redirect plugins let you manage them from the admin panel; for large volumes, combine with server rules
• Shopify: the built-in URL redirects feature, with CSV import for bulk entries. Note the fixed URL formats, such as /products/ and /collections/
• Hosted services such as BASE: redirect options may be limited, so confirm in advance what the old site can forward

Online stores moving to a new cart usually have many product URLs; see e-commerce platform migration for the full process. If you keep the domain and only change hosting, the focus shifts to DNS and email, covered in server migration.

Website migration SEO checklist

The checks before and after launch matter more than the switch itself. Go through this list item by item with whoever does the technical work.

• Before launch: finished redirect map; titles, descriptions and headings carried over; canonicals and internal links updated; XML sitemap ready; GA4 and ad tags installed
• Before launch: save a full list of old URLs plus current rankings and traffic as a baseline
• Launch day: remove noindex, activate 301 redirects, test key redirects in a browser and a checker, test forms and checkout
• Launch day: add the new site to Search Console and submit the sitemap; for a domain change, use the Change of Address tool
• Weeks 1–4: check 404 errors and indexing in Search Console every week and add any missing redirects
• Long term: keep the old domain and redirects for at least a year, ideally longer

The most overlooked item is the old domain's renewal. If it lapses, the redirects stop and backlinks no longer pass value. Keep the domain registered in your own name and know its renewal date.

How UNANOBO handles a migration: the new site as a free demo first

UNANOBO starts by building the destination site as a free demo, based on your current content and brand. While preparing it, we review your current URL structure and suggest which pages to keep, which to merge and how redirects should work.

If you go ahead, the founder personally handles the redirect map, the setup, the launch-day checks and the follow-up in Search Console. You keep one contact throughout, by message in Japanese or English. The process: free demo, feedback, launch, growth.