Migrations need both, and the question is usually asked as though one can replace the other. They cannot, because they are responsible for different failures.
The split
- The developer builds and ships it — the new site, the server configuration, the redirect rules, the deployment.
- The SEO consultant decides what must be preserved — which URLs map where, what content cannot be cut, what to verify before and after.
A developer can implement a redirect map flawlessly. Whether the map is correct is a different question, and answering it requires knowing which URLs carry value — which comes from Search Console data, not from the codebase.
What goes wrong with only a developer
- Redirects mapped by pattern rather than by value, so high-traffic pages get folded into category pages.
- Content trimmed because the new template calls for less of it.
- Metadata regenerated by whatever the new platform does by default.
- Staging directives shipped live — the single most common catastrophic launch fault.
- Nobody watching afterwards, because the project closed at launch.
None of these are developer errors in any meaningful sense. They are decisions nobody was assigned to make.
What goes wrong with only a consultant
- A migration plan nobody implements.
- Redirect rules specified but not deployed correctly at server level.
- Recommendations that are impractical on the chosen platform.
- No verification of what actually shipped.
This is the more common failure in practice: a thorough plan delivered, partially implemented, and never checked. See implementation support.
How to divide it
- Consultant owns the URL map, the preservation list, the pre-launch verification and the post-launch monitoring.
- Developer owns the build, the redirect implementation, the server configuration and the deployment.
- Both attend the pre-launch check. It is the one moment where a missed item is still cheap.
Write down who signs off that the site is ready to launch. Migrations fail in the gap where each party assumed the other had checked.
Frequently asked questions
Can my developer do the SEO side?
Some can. Ask whether they will pull Search Console data to decide the URL mapping. If that is not part of their process, the mapping will be structural rather than commercial.
When should the consultant be involved?
Before the platform is chosen, and certainly before the build. Involving one after launch means paying for recovery instead of prevention. See CMS platform migration.
Is this more expensive?
It adds cost to the project and removes the far larger cost of a botched migration. See website migration SEO cost.
What if the migration already happened badly?
That becomes recovery work. See migration recovery.
Consulting CTA
If a migration is planned, book an SEO consultation before the build begins.