You redraw the menu, tidy the categories, merge a few pages. Perfectly ordinary design work to improve the information architecture. And as a result, addresses change. A URL is the one design artefact whose copies are scattered outside your site, in places you do not control.
What you lose when you lose an address
An address has been quietly accumulating value: links other sites gave it, its position in search results, bookmarks, the path printed in newsletters and on business cards, the destination an advert points at. None of that is under your control, and none of it knows you have changed anything.
That is why a URL change is a design decision. “This structure is better” and “can we afford to give up this address” have to be judged in the same conversation. Settle the structure first and leave addresses for later, and later usually turns out to mean the night of the deployment.
Where addresses change in a redesign
More often than deliberate changes, you get consequential ones. Knowing the list in advance removes most of the surprises.
The last line is the quietest. If both the trailing-slash and non-slash forms resolve, or both www and bare, the same screen holds several addresses — and when one of them disappears mid-redesign you get a 404 that is genuinely hard to trace.
The redirect map is a deliverable
If addresses are changing, build the old to new table. It is not written after the launch; it ships with the launch. The moment the new design goes live, the old addresses must already be redirecting.
Four rules when you build it. First, map one to one — sending ten old addresses to the home page technically works, but nothing those ten had accumulated transfers to the home page. Send each to its nearest new equivalent. Second, no chains: A to B to C adds a round trip every time and accumulates on sites that have been redesigned before. Third, a permanent move is a 301. Fourth, after deployment open every entry — being in the table and actually redirecting are two different facts.
The best decision is usually not to change them
The conclusion follows on its own. If the new design can be drawn on top of the existing addresses, keeping them is always cheaper. Changing a URL because it looks dated means invalidating every copy of it scattered outside your site. Change addresses only when the information architecture genuinely requires it — and when it does, build the table alongside.
How URL changes interact with indexing is covered further in the SEO archive, and migrations, redirects and performance work handled as a single job are part of our optimization program.
Next part
With the address plan settled, it is time to show the work. The next part is reviewing on staging — and what screenshots hide.