Which agency should you choose for a website redesign with SEO?

To choose an SEO website redesign agency, prioritize a team that brings together web development, UX (user experience), content, and SEO from the very start of the project. A redesign is not just a new design: it can help you gain Google rankings, or lose them abruptly. DualMedia, a Paris-based web and mobile agency founded in 2000, illustrates this integrated model with expertise in development, UX/UI, SEO, and digital strategy.

What web and SEO skills need to be brought together?

A good SEO website redesign agency does not just sell mockups. It also knows how to preserve what is already working: pages that attract traffic, content that converts, inbound links, technical structure, and loading speed.

In concrete terms, four roles need to work together before the first line of code: a project manager, a UX/UI designer, a developer, and an SEO consultant. The developer ensures that the site will be maintainable. The SEO consultant checks that Google will be able to explorer, understand, and index the pages. The designer avoids sacrificing conversion for aesthetics.

One point that is often underestimated: the site structure. Changing menus, merging pages, or simplifying a catalog can be an excellent business decision, but a bad SEO decision if the old high-performance URLs disappear without a plan. If your teams are just discovering the topic, this guide on the basics of SEO helps establish a shared vocabulary before the quote.

On the agency side, the reflex is to let the data speak before personal preferences: Search Console, Google Analytics 4, rankings, conversions, indexed pages, Core Web Vitals, and server logs when the site is large. A redesign driven only by the visual identity starts from a weak angle mort.

How can you avoid losing traffic during the migration?

SEO migration is the invisible part of the project. It is also the one that costs the most when it is done poorly. Google recommends, for a URL change, a correspondence between old and new addresses, permanent redirects such as 301 or 308 when lorsque appropriate, self-referencing canonical tags, and up-to-date sitemaps.

The classic trap: deleting pages considered “old” because they are not pretty. Yet some of them capture useful queries or backlinks (links from other sites). Deleting them can sometimes mean cutting off a source of leads without realizing it right away.

Another concrete topic: the preproduction environment, often called staging. It allows you to test the new site before it goes live. But if it can be indexed by Google, you risk publishing unintentional duplicates. A simple password block and meta robots checks (indexing instructions) prevent this problem.

After going live, monitoring should last at least 30 to 90 days depending on the size of the site. The first weeks are used to identify 404 errors, pages sorties from the index, redirect chains, and abnormally sharp drops on strategic keywords.

The SEO steps to integrate into the redesign project

A serious redesign follows a sequence. Not to make the project heavier, but to avoid irreversible decisions made too early. The method below corresponds to the checks recommended by Google and the practices observed in professional site migrations.

1. Exporter all existing URLs from the CMS, Search Console, the XML sitemap, and, if possible, the server logs.
2. Identify the pages to keep, merge, rewrite, or delete based on their traffic, conversions, and business value.
3. Build a correspondence plan between old and new URLs.
4. Plan for 301 or 308 redirects, then test them before launch.
5. Check the title tags, meta descriptions, canonicals, hreflang if the site is multilingual, and meta robots.
6. Update the XML sitemap and check the robots.txt file.
7. Measure the Core Web Vitals: LCP, INP, and CLS, used by Google tools to assess page experience.
8. Monitor indexing, rankings, organic traffic, and conversions after launch.

The Core Web Vitals deserve special attention during a visual redesign. A heavy hero video, a complex carousel, or too many marketing scripts can degrade LCP (largest contentful paint) and INP (responsiveness). To explore this point further, see the useful optimizations for Core Web Vitals.

What SEO deliverables should you request in the quote?

The quote must make it possible to understand what will actually be delivered. A line saying “SEO optimization included” is not enough. It may refer to three title tags just as easily as to a complete migration audit.

At a minimum, ask for a pre-redesign audit, a target site structure, a redirection plan, a list of content to be reused or rewritten, a technical check before launch, and a post-launch tracking dashboard. On the projects we handle, we often see a significant gap between agencies that promise to “think SEO” and those that document every URL transfer.

The before/after indicators must be defined from the start: organic traffic, rankings on priority queries, number of indexed pages, conversions, engagement rate or bounce rate depending on the tool, revenue for e-commerce, and mobile performance. The mobile-first indexing remains a central issue, because Google mainly uses the mobile version to index and rank pages.

At this budget, it is better to reduce the functional scope than to remove the SEO migration. A simpler site that is properly redirected protects your acquisition better than an ambitious redesign launched without a safety net.

What warning signs should make you rule out an agency?

The first warning sign is a promise of increased traffic without an audit. No one can seriously predict an SEO gain without knowing the current situation, the competition, the content, the domain’s authority, and the site’s technical quality.

Second warning sign: the agency talks only about CMS or technology. WordPress, Symfony, Laravel, Next.js, or a headless WordPress can all be relevant depending on the context. Honestly, a headless architecture is only justified if you have real needs in terms of performance, security, multichannel delivery, or technical governance; for a standard showcase site, it can add cost and complexity. This topic is covered in detail in the analysis on Headless WordPress for a business website.

Third warning sign: no testing phase. Testing is the verification before going live. It should include forms, tracking, redirects, 404 pages, performance, mobile display, GDPR notices, and admin access.

Finally, be wary of a timeline that is too short. Redoing an 80-page corporate site in two weeks may seem appealing. In practice, the trade-offs are paid for later: content copied in haste, forgotten redirects, missing tracking, decisions approved without data.

What budget should you plan for an SEO website redesign agency?

For a French SME, a realistic order of magnitude starts at around €5,000 before tax for a limited showcase redesign, if the content is under control and the number of pages remains low. A corporate site with brand, SEO, content, and migration stakes is more likely to start at around €10,000 before tax, then increase with volume, languages, e-commerce, or business integrations.

These amounts correspond to the ranges published by DualMedia in 2026: showcase site from €3,000 to €8,000 before tax, institutional site from €10,000 to €30,000 before tax, e-commerce from €8,000 to €40,000 before tax. The stated timelines also vary: 4 to 8 weeks for a showcase site, 8 to 16 weeks for a corporate site, 8 to 20 weeks for e-commerce.

Monthly SEO after a redesign depends on the level of support: content production, technical analysis, link building, competitive monitoring, reporting. Some French providers range from a few hundred to several thousand euros per month. The right question is not “how much does SEO cost?” but what actions will actually be carried out each month.

If your site runs on WordPress, also add security to the scope. A redesign is the right time to review plugins, user permissions, backups, and hosting, for example with OVH or behind Cloudflare depending on the need. The guide on WordPress hardening in 2026 lists useful checks.

How should you evaluate the agency before signing?

Ask for a scoping meeting with the people who will actually do the work. Not just the salesperson. You need to hear how the agency would arbitrate a conflict between design, budget, timeline, and SEO.

A simple grid is enough: technical skills, SEO methodology, UX quality, measurement of results, project governance. For each area, require an example of a deliverable: audit, mockup, backlog, redirection plan, bord dashboard, testing schedule. A solid SEO website redesign agency is willing to discuss limitations and risks.

Also look at the ability to explain. If you don’t understand why a recommendation is being made, the problem isn’t necessarily you. A provider that explains things clearly during the pre-sales phase will be more likely to get your teams on board properly during the project.

Defining this type of project upfront avoids most unpleasant surprises. When the redesign affects SEO, an outside perspective is especially helpful for prioritizing: what absolutely needs to be protected, what can be improred now, and what can wait for a second phase.

FAQ on choosing an agency for an SEO redesign

Which agency should you choose to redesign a website without losing its SEO?

Choose an agency that provides an initial audit, a redirection plan, technical checks, and post-launch monitoring. If these deliverables are not included in the quote, the risk of traffic loss increases.

How much does a website redesign with SEO cost?

For an SMB, expect often between €3,000 and €8,000 excl. tax for a showcase website, and rather €10,000 to €30,000 excl. tax for a corporate website. The budget increases with the number of pages, languages, e-commerce, and integrations.

Does a redesign automatically improve SEO?

No. It improves SEO if it corrects technical issues, clarifies content, and protects high-performing URLs. A poorly migrated redesign can, on the contrary, reduce traffic, rankings, and conversions.

Should old URLs be kept during a redesign?

When possible, keeping performant URLs limits the risk. If they change, permanent 301 or 308 redirects must be planned and their operation must be checked after going live.