Website Migration: Complete Definition and Guide

What is a website migration?

A website migration is the process of transferring a website from one technological environment to another. This transfer may involve the CMS platform (for example, from WordPress to Wagtail), the domain name, the protocol (HTTP to HTTPS), the hosting or the URL structure. It is a complex operation that simultaneously affects content, data, search engine rankings, performance and user experience.

Migration is typically motivated by limitations of the existing platform: insufficient performance, maintenance difficulties, lack of flexibility, excessive hosting costs or technological obsolescence. It represents an opportunity to modernise an organisation's entire digital presence while preserving hard-won search engine rankings and traffic.

The main challenge of a migration lies in preserving the SEO capital accumulated over the years. A well-ranked website on Google can lose a significant share of its organic traffic if the migration is poorly planned. This is why 301 redirect strategy and link structure preservation are critical elements of any migration project.

Why it matters

Website migration is a pivotal moment in an organisation's digital life. Well executed, it paves the way for accelerated growth; poorly managed, it can have devastating consequences on traffic and revenue.

• Technological modernisation: migrating to a modern platform delivers better performance, simplified maintenance, advanced features and improved security. Open-source CMS platforms like Wagtail offer flexibility and scalability that ageing proprietary solutions cannot match.
• Performance improvement: a platform change is the opportunity to optimise load times, Core Web Vitals and the mobile experience. These improvements directly impact search rankings and conversion rates.
• Cost reduction: some platforms impose licences, maintenance fees or disproportionate hosting costs. Migrating to an open-source stack (Django, Wagtail, PostgreSQL) can significantly reduce operational costs.
• Editorial autonomy: modern CMS platforms offer intuitive admin interfaces that enable non-technical teams to manage content independently, without relying on a provider for every change.
• Compliance and security: migrating to a modern, maintained platform addresses current security requirements (HTTPS, regular updates, vulnerability protection).

How it works

A website migration is a structured process that unfolds in several distinct phases, each demanding meticulous attention to detail.

The audit phase is the first step. It involves cataloguing all content, pages, media and features of the existing site. The SEO audit is particularly important: it records all indexed URLs, keyword positions, backlinks and organic traffic per page. This audit serves as a baseline for measuring the migration's impact.

Redirect planning is the most critical step for SEO preservation. Every URL on the old site must be mapped to its equivalent on the new site via 301 (permanent) redirects. This mapping must be exhaustive: a forgotten URL means a broken link and a potential loss of ranking.

Data migration covers the transfer of content (text, images, documents), metadata (titles, descriptions, tags), user accounts and all structured data. Automated migration scripts are typically developed to transform data from the source format to the target format.

New site development proceeds in parallel on the new platform. Information architecture, design, features and integrations are designed and implemented. The site is thoroughly tested in a staging environment before going live.

Go-live is the switch-over moment. Redirects are activated, DNS is updated if necessary, and the old site is replaced by the new one. This step is followed by an intensive verification phase: checking redirects, content, features and analytics tracking over the following weeks.

Concrete example

The migration of the Fonds Reine Mathilde website, carried out by KERN-IT, illustrates the challenges and methodology of a successful migration. The original site was built on WordPress and suffered from limitations in performance, editorial flexibility and maintenance.

KERN-IT conducted a complete migration to Wagtail CMS: exhaustive audit of the existing site, mapping of all URLs, content and media migration via automated Python scripts, complete interface redesign with TailwindCSS, and implementation of a 301 redirect strategy to preserve acquired search rankings. The new platform offers an intuitive admin interface, improved performance (optimised Core Web Vitals) and full editorial autonomy for the Fonds team.

This type of WordPress-to-Wagtail migration is representative of a broader trend: organisations that have reached WordPress's limits are seeking more robust, performant and flexible alternatives. Wagtail, built on Django and Python, offers a modern architecture, full control over the data model and code quality that facilitates long-term maintenance.

Implementation steps

1. Audit the existing site: catalogue all pages, content, media, features and integrations. Conduct a complete SEO audit (indexed URLs, positions, backlinks, traffic per page).
2. Plan redirects: create an exhaustive mapping between old URLs and new ones. Verify that every important page on the old site is covered by a 301 redirect.
3. Develop migration scripts: write automated scripts (Python) to transform and transfer content, media and metadata from the source CMS to the target CMS.
4. Design and develop the new site: build the new site on the target platform with a modernised design, optimised performance and all required features.
5. Test in staging: run exhaustive tests in a staging environment: content, redirects, features, performance, responsive design, forms, integrations.
6. Execute the switch: deploy the new site to production, activate redirects, update DNS if necessary. Schedule the switch during a low-traffic period.
7. Monitor post-migration: verify redirects with Google Search Console, monitor organic traffic, fix 404 errors and indexing issues during the weeks following migration.

Related technologies and tools

• Wagtail CMS: modern Django-based CMS, a robust and flexible alternative to WordPress offering full control over the data model and an intuitive admin interface.
• Python: language used to write data migration scripts, transforming content from the source format to the target format in an automated way.
• Google Search Console: essential tool for monitoring indexing, crawl errors and the migration's impact on search rankings.
• Screaming Frog: SEO crawler used to audit old site URLs, verify redirects and detect broken links after migration.
• TailwindCSS: utility-first CSS framework enabling rapid design modernisation during migration while ensuring optimal front-end performance.

Conclusion

Website migration is a strategic operation that, when well executed, modernises a digital presence while preserving the SEO capital accumulated over the years. The key to success lies in planning rigour, redirect exhaustiveness and migration script quality. KERN-IT, through its work for the Fonds Reine Mathilde, demonstrates that a WordPress-to-Wagtail CMS migration can be conducted methodically to deliver a more performant, flexible and autonomous site without loss of search rankings.