Website Migration Guide · Technical

How to Create a URL Mapping for a Site Migration

A URL map is the backbone of safe redirects: every old URL matched to the right new one. Here is what a URL map is, why it matters so much, and how to build one so no page is left without a destination.

Updated: July 2026
Written by: Andrew Odgers, Managing Director
Reading time: 6 minutes
The short answer

A URL mapping is a document that lists every existing URL and the new URL it should point to after the migration, so each old address has a defined destination. It matters because redirects can only be correct if the mapping behind them is correct. You build one by crawling the current site, pulling in analytics and Search Console data, and matching each old URL to its closest equivalent. Where a page has no exact match, map it to the most relevant related page rather than the homepage. The finished map is the source your 301 redirects are built from.

The backbone of safe redirects

What a URL map is, and why it matters so much

A URL mapping is a document that lists every existing URL on your site and the new URL it should point to after the migration, so each old address has a defined destination. It is the master reference that your 301 redirects are built from; because it decides where every page ends up, the URL map is the backbone of a safe migration. URL mapping is so important because redirects can only be correct if the mapping behind them is correct, so a complete, accurate URL map is what makes sure no page is left without a destination and no ranking signal is lost. A missed or wrong mapping becomes a broken redirect or a lost page; because the redirects depend entirely on it, getting the URL map right is one of the most important tasks in the whole migration, and it sits at the heart of any good migration plan.

M 01

Every URL listed

Old address to new destination.

M 02

Prioritised

Most valuable pages first.

M 03

Feeds the redirects

The source of every rule.

Building it, handling gaps and feeding the redirects

How to create the map, pages without a match, and the link to redirects

You create a URL map by crawling the current site to list every URL, pulling in analytics and Search Console data to see which pages matter most, then matching each old URL to its closest equivalent on the new site, deciding case by case where structures differ. Prioritising by traffic and links makes sure the most valuable pages are handled first; because it is detailed work, a careful, spreadsheet-based process is the reliable way to build a complete map. Where a page has no direct equivalent, you map it to the most relevant related page, such as a parent category or a closely matching topic, rather than leaving it to break or sending it to the homepage. A relevant destination preserves more value and gives users a sensible landing point; because a good near-match is far better than a dead end, every old URL should map to the most relevant available page. The URL map connects to redirects because it is the source your 301 redirects are built from, so once it is complete and checked, each old-to-new pair becomes a redirect rule that guides search engines and users to the right place. A verified map means the 301 redirects can be implemented accurately. Because the redirects are only as good as the map, a complete, tested URL mapping is what makes the redirect step safe.

SEO done properly, from £350 a month

Every page accounted for.
Nothing left to break.

The URL map is where a safe migration is won or lost. We crawl your whole site, prioritise by traffic and links, and match every old URL to the right new one, mapping near-misses to the most relevant page, so the redirects that follow are complete and accurate.

Everything included in your plan:

Google Maps optimisation Full website management Local SEO campaign AI optimisation (GEO) Facebook, Instagram and LinkedIn Quarterly audits Monthly reporting
£350 per month

One clear retainer. No setup fee.

Frequently asked

URL mapping for site migration

What is a URL mapping for a site migration?
A URL mapping is a document that lists every existing URL on your site and the new URL it should point to after the migration, so each old address has a defined destination. It is the master reference that your 301 redirects are built from. Because it decides where every page ends up, the URL map is the backbone of a safe migration.
Why is URL mapping so important?
Because redirects can only be correct if the mapping behind them is correct, so a complete, accurate URL map is what makes sure no page is left without a destination and no ranking signal is lost. A missed or wrong mapping becomes a broken redirect or a lost page. Because the redirects depend entirely on it, getting the URL map right is one of the most important tasks in the whole migration.
How do you create a URL map?
You crawl the current site to list every URL, pull in analytics and Search Console data to see which pages matter most, then match each old URL to its closest equivalent on the new site, deciding case by case where structures differ. Prioritising by traffic and links makes sure the most valuable pages are handled first. Because it is detailed work, a careful, spreadsheet-based process is the reliable way to build a complete map.
What if a page has no direct equivalent?
Where a page has no exact match on the new site, you map it to the most relevant related page, such as a parent category or a closely matching topic, rather than leaving it to break or sending it to the homepage. A relevant destination preserves more value and gives users a sensible landing point. Because a good near-match is far better than a dead end, every old URL should map to the most relevant available page.
How does the URL map connect to redirects?
The URL map is the source your 301 redirects are built from, so once it is complete and checked, each old-to-new pair becomes a redirect rule that guides search engines and users to the right place. A verified map means the redirects can be implemented accurately. Because the redirects are only as good as the map, a complete, tested URL mapping is what makes the redirect step safe.