With any website migration or rebuild there are quite a few moving parts. Accounting for all of them is of paramount importance to ensure a smooth transition and minimize any SEO issues that can crop up. While the following information is mainly concerned with smaller site migrations (<1000 pages) the same general concepts would apply to much larger sites — although the implementation of the fixes would require a different skillset.
Check URL structure
Often when redesigning or moving a site from one CMS to another, the URLs of the site’s content will change. While this isn’t necessarily a bad thing, it is important to account for these changes to ensure Google is able to recognize and index the updated URLs.
There are two main options of dealing with the URL issue: the first is to simply update the URLs on the new site to match the URLs on the old site. The second method is to 301 redirect the URLs that existed on the old site (but not the new site) to their equivalent page(s) on the new site. With the 301 approach it is important to ensure that each link only goes through a single redirect whenever possible, eventually GoogleBot will stop following redirects if there are too many chained together.
Adjusting the general URL structure to be more SEO friendly can also be helpful at this stage, organizing similarly related pages in descriptive subdirectories can be useful for bots as well as users — remember to always add redirects to ensure the content can easily be found by GoogleBot at the new location
It is always a good idea to spend some time and do a thorough content check before officially launching the rebuild. For example, with a site that has a large number of blog posts it is important that everything gets moved over properly, import scripts can time out and a myriad of other issues can crop up, also remember to look for standalone/orphan pages that may exist on the original site but won’t be found by traditional web scrapers..
With content, also check the sites top URLs in Google Search Console, make sure the content on those URLs is recreated on the new site, and the proper redirects are in place so GoogleBot can find the content if it is in a different location.
Because those are the highest value pages in terms of search, it is very important they are present on the new site.
Check analytics, other tracking scripts, and look for any validation files
Look through the old site and identify any tracking scripts (Google Analytics, Facebook, Hotjar, etc) that should be moved over to the new site. Also, check for validation files and validation meta tags that may need to be migrated. This can be a great time to reevaluate what third party scripts related to analytics you do/don’t need.
If necessary, check PPC campaigns, ensure URLs on that side are updated, “Thank You” pages & goals are adjusted as needed, and that any conversion snippets are moved over.
Check all user submission services (forms, chat, phone numbers, etc.)
Take note of the types of submissions users can make use of on the original site and how the data is handled (send an email notification to a recipient, submit data to an API, etc.). Make sure that the redesign continues to send any user submitted information to the correct people & services that need it.
Check site with 3rd party tools to ensure as many on-site technical SEO errors are corrected as possible
Depending on the size of the site, this may be a very daunting task. Use a third party tool like Screaming Frog or a service like SEMRush to identify issues that may impact the technical optimization of your site from an SEO perspective. Fix these errors where possible (there will rarely be a better time than during a redesign/rebuild). Check for things like internal redirects, 404 errors, missing/duplicate h1 tags, missing alt text on images, etc. Most tools will spell out exactly what items you need to fix.
Verify tracking and verification scripts
Double check the tracking and verification scripts to ensure everything is working as expected. There is nothing worse than checking analytics one week down the road to see how a rebuild affected SEO only to find out that there is no data available.
Double/triple check anything and everything involving PPC, if possible pausing campaigns during the initial launch window can be helpful — give you and your PPC team time to make sure everything is ready to go before the campaigns are reenabled.
Check pages indexed in Google to make sure everything is directed or redirected properly
After a rebuild where URLs or content have changed or been moved around, perform a “site:” search and click on the linked pages in the results. This is a quick way to confirm redirects are working properly - if they aren’t add redirects for any pages wrongly returning a 404 error from the results.
Ensure SSL certificates are still functional and redirecting properly, look for mixed content warnings
In addition to making sure the SSL certificates are functioning properly, check for mixed content errors. With the rebuild (especially if the original site was loaded over http), it is very possible there are some images in the content, or scripts loading resources over HTTP instead of HTTPS. A service like Why No Padlock? Can help track down which resources on any given URL are causing issues.
Double check general SEO indexing and add schema markup where possible (Breadcrumbs, general site schema, etc.)
After deploying a site redesign or rebuild check the robots.txt file and look for any robots meta tags. Ensure any global ‘noindex’ rules from the development environment are not present on the production (live) version on the site.
Monitor site closely for issues
Now that your site is newly re-launched, it is time to closely monitor the site status (look at SEO rankings, visitor traffic, server issues, performance benchmarks, etc.). There are tons of moving parts with a moving a new site live and the quicker issues can be addressed the better. Some tools I would recommend to monitor things and look for any oddities: SEO - Screaming Frog, SEM Rush, Google Search Console, Traffic - Google Analytics, Server Issues - Log files, Screaming Frog Log File Analyzer.