Website migration: definition, steps and risks
Changing CMS, domain, site structure or design: every website migration affects URLs and rankings. What it covers, its steps, its risks and its cost.
A website migration is any significant change to a site's addresses, content, structure or platform: a new CMS, domain name or host, a reworked site structure or design, several sites merged into one. In every case, what Google knew about the site changes, and the rankings it had earned can be lost if the move from the old site to the new one is not prepared.
This article gives the full picture. Each point has its own article to go further: the reasons to migrate a website, the types of migration and their scope, the preparation phase, the mistakes to avoid and SEO migration and its steps.
What a website migration covers
Not every migration carries the same risk. They fall into four families:
- technical migration: a new CMS, server or host, a switch to HTTPS. A CMS change almost always changes the URLs; a well-sized change of host almost never does;
- domain name migration: every URL on the old domain must lead to its equivalent on the new one;
- editorial migration: content and site structure are rewritten, pages are merged or removed;
- design migration: new templates, new navigation, often with new categories.
A redesign often combines several families at once, which multiplies the risks. Each one is detailed, together with how to set its scope, in our article on the types of website migration.
Why a website migration is risky
A site's rankings rest on the relevance of its content, its internal linking, its technical quality and the links it receives from other sites. A migration can damage each of these pillars:
- content: rewritten, shortened, or no longer matching the search intent;
- internal linking: link blocks disappear, a mega menu spreads authority across too many pages;
- technical quality: slower load times, forgotten structured data, an indexed staging site, pages blocked by robots.txt;
- external links: without URL-by-URL redirects, links that pointed to the old pages lead to 404 errors and their benefit is lost.
The risk is not only about Google. The chosen CMS must cover the old site's features: a service or product that disappears for lack of a module means lost revenue. And a new design upsets regular visitors' habits, especially on an e-commerce site: have a few users test the new site before launch (see visitor dissatisfaction during a migration).
A drop in traffic is not inevitable: it almost always comes from a step done badly. The most frequent cases are gathered in our article on the mistakes to avoid in a website migration.
The steps of a website migration
- Decide and frame: why migrate, what to migrate, with which team and when. The reasons to migrate shape the scope, and the date is chosen outside peak periods (see when to build the migration plan).
- Prepare: backup, inventory of URLs and content, baseline measurements, audit, SEO specifications for the developers. This is the subject of our article on the preparation phase of a migration.
- Build the redirect plan: each old URL gets its new address, the closest one by content, never the home page by default (see the redirect plan).
- Test on the staging site: redirects, internal links, tags, robots.txt, XML sitemap, no 404 errors on the pages that matter.
- Go live and check: redirects replayed on production, sitemap submitted in Search Console, indexing and traffic monitored over the following weeks.
The search side of these steps is developed in our SEO migration guide, and our migration checklist covers them point by point.
How much a website migration costs
The cost of a migration is not limited to the service or the tool. For a while you often pay for two hosting plans, renew two domain names, maintain two technical solutions, and need the teams' time for acceptance testing. These items are often left out of the budget. Orders of magnitude are in our article on the price of a website migration service.
Who runs the migration
A migration brings together people who do not always work together: project manager, developers, SEO specialist, writers, and the business people who know which pages bring in revenue. If you lack experience of good practice, get help from a specialised consultant or agency, and involve the SEO specialist from the mock-up stage, not after launch. See the redesign team.
What Swan takes care of
The redirect plan is the longest step to do by hand. Swan crawls the old site and the staging site, extracts the content of each page and suggests, for each old URL, the pages of the new site closest in content. You approve or choose, and Swan checks the redirects on the staging site and then on production, and exports them. URLs imported from Search Console or pasted from your link tools and server logs keep their origin, so you can handle the ones that matter first.
Preparing a website migration? Swan matches your old and new URLs and checks your redirects before launch.
