Free tool
Website migration audit checker
Paste the old URL list, the redirect map and the new site URL list. The checker shows which old pages have no destination, which destinations do not exist on the new site, and where the map has chains, loops or homepage catch-alls.
Short answer: A website migration audit compares three lists: every old URL you want to keep, the redirect map, and the URLs that exist on the new site. An old URL with no rule will 404 after launch, a rule pointing at a URL the new site lacks sends visitors to an error, and chains, loops and conflicting rules waste crawl time or never resolve. This browser tool runs those checks on lists you paste in and exports the findings.
Planning a replatforming, redesign or domain move? See our SEO migration services.
Audit results
Paste at least one list to see results. This needs scripting on.
What each check means
The checks follow the guidance in Google Search Central's page on site moves with URL changes (read Nov 10, 2026). Severity is this tool's own ranking of how much a finding usually costs on launch day.
| Check | Severity | What it means and what to do |
|---|---|---|
| Old URL with no rule | High | The page will 404 after launch unless a pattern rule covers it. Map it, or decide on purpose that it is gone. |
| Destination missing from new site | High | The rule points at a URL the new site does not list, so visitors and crawlers land on an error. Fix the destination or add the page. |
| Loop | High | A rule that leads back to itself never resolves. Browsers show a too-many-redirects error. |
| Conflicting rules | High | One old URL has two different destinations. Servers use whichever rule they read first, so the result depends on file order. |
| Chain | Medium | A destination is itself redirected. Point the first rule straight at the final URL. |
| Homepage catch-all | Medium | Many old pages sent to the home page can be treated as soft 404s. Use it only for pages with no real equivalent. |
| Rule for URL not in old list | Low | Usually an incomplete crawl or a map built from a different crawl. Check which list is stale. |
| Destination with query string, fragment, http or mixed case | Low | Destinations should match the canonical form of the new URL. Parameters and fragments rarely belong in a redirect target. |
| Mixed trailing slashes | Low | Destinations written both with and without a final slash invite an extra hop on the new server. |
Before and after launch
This checker works on lists, so run it before cutover. After cutover, crawl the old URLs and confirm each one returns a single redirect to a live page, then update the sitemap and watch Search Console for errors. Our SEO migration checklist lists every step in order.
Need rules for the server? The redirect map generator turns a clean map into Apache, Nginx or Cloudflare rules. For a hands-on review, see SEO migration services, or return to all free SEO tools.
Questions about migration audits
What does this checker compare?
It compares three lists you paste in: every old URL you want to keep, the redirect map (old URL to new URL), and, optionally, every URL on the new site. It reports old URLs with no rule, rules that point at URLs missing from the new site, conflicting rules, chains, loops and homepage catch-alls. It does not fetch any URL, so it cannot tell you what a live server returns. Run a crawl against the finished redirects as the last step.
Why should every old URL have its own destination?
Google Search Central (Site moves with URL changes, developers.google.com/search/docs/crawling-indexing/site-move-with-url-changes, read Nov 10, 2026) says to map each old URL to its new counterpart, and advises against sending many old URLs to one unrelated page such as the new home page, because that can confuse users and may be treated as a soft 404. Redirecting several old pages to one new page is fine when you merged their content into it.
How long should the redirects stay in place?
The same Google Search Central page (read Nov 10, 2026) says to keep redirects for as long as possible, generally at least 1 year, so Google can transfer signals to the new URLs, and notes that users may benefit from keeping them longer. It also says to update your sitemaps to the new URLs and to update your own links and high-volume external links.
Does it matter if the old list and the map disagree?
Yes. An old URL missing from the map returns a 404 after launch unless a pattern rule catches it, and a rule for a URL missing from the old list usually means the crawl was incomplete or the map came from a different crawl. Both are cheap to fix before launch and slow to notice afterwards. The checker lists each case so you can decide whether the gap is deliberate.
Is my URL list uploaded anywhere?
No. The parsing and comparison run in your browser with JavaScript. Your staging hostnames, path structures and redirect rules stay on your device. The exported files are built locally too.
Book a call with us
A 30-minute call in your working hours. Tell us what you sell and where, and we will tell you what we would do first and what it involves. Prefer email? Send your website through the form and the Passieon Team will reply by email.