#1. Setup the new website on a temporary URL. Edit Robot.txt and make it not crawlable.
Syntax
User-agent: *
Disallow: /

#2. Test new website for broken links
Use Xenu to check for broken links
http://home.snafu.de/tilman/xenulink.html
Fix all broken links before migration

#3 – Create a list of all pages from your OLD website and create a site map

#4 – Create page-by-page 301 redirections to redirect old URL's to new URL'S
.htaccess file is where you edit for redirection
All URL in the site map should be redirected

#5- Switch to the new website (all at once)
Google recommends to migrate everything once

#6- Make sure that the new website is verified with Google Search Console
Google console -- https://search.google.com/search-console/welcome

#7- In Google Search Console, use the URL INSPECTION and make sure Google can properly read and index your new site

#8- Check robots.txt
Make sure robots.text are proper and there are no issue blocking any pages or URL

#9- Optimize and resubmit XML sitemap to Google and Bing
Using Google Console

#10- Monitor your rankings
Make sure you have a monitoring system in place before and after you do a website redesign.

Bonus 1 : Make sure you monitor the bounce rate for your site before and after redesign.
Bonus 2 : if your social media count becomes zero immediately after the redesign don't panic.

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