Redirect map checklist for a site migration
Most migration traffic losses come from the redirect map, not the new site. Here is what to check in the spreadsheet before launch, and why each check matters for search engines and visitors.
Why check the map before launch
A redirect map is usually a spreadsheet with two columns: the old URL and the new URL. It is edited by several people, merged from exports and patched late. Mistakes in it are cheap to fix while it is still a file and expensive once it is live: every broken redirect costs crawl budget, link equity and real visitors until someone notices. Checking the map as text also works for new URLs that do not exist yet, which a crawler cannot test before launch.
1. Redirect chains
A chain is a redirect whose target is itself redirected: /a → /b → /c. Each extra hop slows the page down and search engines may stop following after a few hops. Google advises redirecting straight to the final destination. Count the hops for every source and collapse each chain so the first URL points directly at the last one.
2. Loops and self-redirects
A loop sends a URL back to itself through other rows, for example /a → /b → /a. A self-redirect points a URL at itself. Both end in a browser error, and a single loop can hide inside thousands of rows. Treat every loop as a launch blocker.
3. Duplicate sources and conflicting targets
The same old URL sometimes appears twice with different targets, often after two lists are merged. Your server will use one of them and silently ignore the other, so the result depends on rule order. Find every source that appears more than once and decide which target is correct.
4. HTTPS to HTTP downgrades
A redirect from an https:// URL to an http:// one usually comes from an old export. It weakens security, triggers browser warnings and adds another hop when the HTTP URL redirects back to HTTPS. Every target should use the final scheme and host.
5. Dropped query strings
If the old URL carried parameters such as ?id=42 or campaign tags and the target drops them, filters, product variants and tracking can break. Check which rows lose a query string on the way and whether that is intended.
6. Matching rules
Decide up front how URLs are compared: scheme and host are case-insensitive, default ports and #fragments do not matter, but paths and query strings usually do. Use full URLs for cross-domain moves and paths for same-domain moves, and do not mix the two for the same source.
After launch
Once the redirects are live, crawl a sample of old URLs, watch the server logs for 404s, and keep the old sitemap submitted for a few weeks so search engines revisit the old URLs and see the redirects.
Check it automatically
To run these checks on your own map, Redirect Map Lint reads a CSV or TSV map of up to 5,000 rows and reports chains with hop counts, loops, self-redirects, duplicate sources, conflicting targets, HTTPS downgrades and dropped query strings, plus a flattened map where every chain points straight at its final destination. The map is checked as text and is not stored. Three checks are free; the monthly plan is $9.