Website redesign: how not to lose your SEO

Your website is a few years old, it’s slow, it doesn’t display well on mobile and it no longer reflects your business. You decide to redo it. Three weeks after launch, the calls dry up: your website has disappeared from the first page of Google. This scenario is unfortunately common, and almost always avoidable.

Why does a redesign make SEO drop?

Google has spent years understanding your website: which pages answer which searches, which websites link to you. A redesign can wipe out this history in an instant. The most common causes:

• URLs changed without redirects: the pages Google knew return a 404 error.
• Pages deleted even though they generated traffic.
• Content rewritten without regard for the keywords it ranked for.
• Tags lost: titles, descriptions, image alt attributes.
• A website blocked from indexing: the protection set up during development is forgotten at launch.

Step 1: audit the existing site before touching anything

Before any mock-up, you need to know what works. In Google Search Console, export the pages that receive clicks and the associated queries. Supplement this with a crawling tool to list all the website’s URLs, and with a link analysis tool to spot the pages that receive external links.

You end up with a list of high-value pages: they’ll need to be kept, or redirected to an equivalent page.

Step 2: build the 301 redirect plan

Every old URL must point to the closest new page through a permanent redirect (code 301). That’s the signal that tells Google the page has moved and that it can transfer its history to the new address.

Step 3: preserve and improve high-performing content

A redesign is an opportunity to improve your copy, not to replace it blindly. For each strategic page, keep the keywords that generate traffic, enrich the content and update the information. Weak or duplicate pages can be merged.

Step 4: get the new website’s technical side right

This is often where a redesign gains rankings. A modern website must be fast, display perfectly on mobile and offer clean code that Google crawls easily. Check before launch:

• the title and description tags of each page;
• the heading structure (only one H1 per page);
• the robots.txt file and the sitemap (sitemap.xml);
• structured data (business, FAQ, breadcrumb);
• mobile performance scores, measured with PageSpeed Insights.

To understand why speed matters, read our article on Core Web Vitals, and for choosing the architecture, our article SSR, SSG or CSR.

Step 5: monitor the weeks after launch

On launch day, submit the new sitemap in Search Console and test a sample of redirects. Over the following weeks, monitor crawl errors, the indexing of new pages and how your rankings evolve. A slight fluctuation is normal; a lasting drop must be analysed quickly.

In short

A successful redesign is prepared as much as it is built: audit, redirect plan, preserved content, careful technical work and follow-up after launch. Done well, it improves not only your business’s image but also your visibility. That’s exactly the method we apply to our website redesigns in Marseille.