Rebuilding or moving a site without losing what search already knows.

A rebuild can change a site's design, its CMS, its content and its URLs, and each of these is a separate risk. Google's guidance on site moves says to change only one thing at a time. Its example is a site that wants a new domain, a new CMS and a new layout: do them one after another rather than together. Whether that is practical is a project decision, but it shows how Google thinks about the risk.

The same page sets out what to prepare. The new site should be tested thoroughly. Robots.txt and noindex rules used while the site was in development must be reviewed and removed when the move starts, so a development block does not carry over to the live site. Content that is not being carried across should return a 404 or 410. Each new URL should have a self-referencing canonical tag, internal links should point at the new URLs, and the server needs capacity for the heavier crawling Google may do after a move.

Google suggests timing a move for a period of lower traffic if possible, so fewer people are affected by any problems. It also says a move is complete only once Googlebot has visited every old and new URL at least once, because the move happens URL by URL. Google also says to expect temporary ranking fluctuation. For medium-sized sites it can take a few weeks or more for Google to show the new URLs, and longer for larger ones.

A rebuild that must not lose organic visibility is a good fit for our work. We cover website rebuilds with a search-friendly architecture, and with redirects mapped before launch and tested after. Our article on SEO changes that need sign-off before launch is relevant here.

Google treats two kinds of move separately. A move that changes URLs, such as HTTP to HTTPS, a new domain or new paths, follows the site move guide. A change of hosting or a CDN that leaves visible URLs alone follows a separate guide on changing hosting, which covers lowering DNS TTL values in advance, testing on a temporary hostname with noindex, making sure a firewall does not block Googlebot, and shutting down the old hosting only when traffic to it reaches zero.

Where URLs change, redirects do the work. Google's redirects documentation says permanent redirects tell Google the target should be canonical, while temporary redirects keep the source page in results. The site move guide recommends server-side permanent redirects such as 301 and 308 and says they do not cause a loss in PageRank. It advises redirecting to the final destination, keeping chains short (ideally no more than three redirects), and not sending many old URLs to one irrelevant page such as the home page, which may be treated as a soft 404. Redirecting old pages to a single new page is fine if their content was consolidated there.

On sequencing, Google recommends that small and medium sites move all URLs at once, which helps its systems detect the move and update the index faster, while larger sites can move one section at a time to make problems easier to monitor and fix. Domain moves also need a Change of Address in Search Console, which Google says is not needed for HTTP to HTTPS, www changes or path moves on the same domain.

Our Technical SEO service handles migrations: planning, redirect mapping, testing, launch monitoring and recovery, for single sites and multi-market structures. See migrations for the detail.

Architecture is what a rebuild gets to decide, and what a migration has to preserve. Google's URL structure guidance favours descriptive, readable URLs, hyphens, minimal parameters and a reminder that URLs are case sensitive. The SEO Starter Guide says that grouping similar pages in directories can help Google on sites with more than a few thousand URLs.

Google can only discover links that are a elements with an href, according to its JavaScript SEO basics. Under mobile-first indexing, Google uses the mobile version of content for indexing and ranking, and advises that mobile and desktop carry equivalent content and the same structured data. Structured data should describe content visible on the page, and Google recommends JSON-LD in most cases. Canonicalization, per Google, draws on signals including redirects, sitemaps and rel="canonical" annotations, as a hint rather than a rule. The site move guide also asks for a sitemap of the new URLs, and the sitemap guide says Google uses the lastmod value only when it is consistently and verifiably accurate.

We build with this in mind: logical, stable, human-readable URLs; semantic HTML with real headings; structured data designed together with the content model; and redirects mapped before launch. How a site's structure is analysed or planned is covered under architecture in Technical SEO.