February 19, 2020
10 minutes

How We Migrate Large Websites Without Losing Any SEO

Migrating a large website with hundreds or thousands of pages is a complex and risky procedure for any company. It’s cause for even more concern when the website relies on search engines to drive the bulk of its traffic.

We have all heard of horror stories related to website migrations going bad and wiping out a company's search engine rankings overnight. As a result, we wanted to create a guide on how to properly migrate a website without losing SEO traffic, as well as pass along a few insider tips from our experience of building and migrating dozens of enterprise-size websites.

Click here to review the source.

This article highlights SEO best-practices that can be followed during the website migration process and is divided into three bite-size sections: Pre-Launch, Launch, and Post-Launch

In the Pre-Launch section, we cover items that set the foundation for a smooth transition from the old website to the new website. In this section, we touch on topics like SEO auditing, URL mapping, redirection maps, canonicalization, on-page considerations, and internal linking.  

In the Launch section, we emphasize the importance of vigilance towards key performance metrics like ranking keywords and overall traffic. This is also the section where we discuss sitemaps.  

Lastly, in the Post-Launch section, we share tips and additional improvements that website owners can make during the migration process of a large website.

Website Migration Basics

Before we jump into our recommendations for each stage of the site migration process, I wanted to quickly touch on a few basic points like objectives and types of migrations.

Website Migration SEO Objectives

Setting objectives is key to running a smooth website migration. Despite our experience that objectives are different from project to project, they all seem to consistently share these three themes:

  1. Minimize search engine traffic fluctuation
  2. Expedite website indexation, transfer of authority, and visibility
  3. Protect your investment in your old website (structure, backlinks, social bookmarks)

Types of Website Migrations

Apart from having a varying range of objectives, there are also a wide variety of “types” of website migrations. A few common ones we have dealt with are:

  • Website Redesign (leading to new URLs)
  • Switching Hosting Provider
  • Migrating CMS
  • Changing Top-level Domain Name
  • Changing Site Structure  
  • Switching Subdomain to Subfolder
  • Non-Secure to Secure


Anytime before actually flipping the switch from your “old site” to your “new site” would be, for the context of this article, considered the “Pre-Launch” stage. In this stage you're planning out the migration, laying the groundwork, and tracking your “pre-launch” numbers so you can compare them to the “post-launch” numbers. From a birds eye view, you are doing 80% of the SEO migration work in this stage.

Technical Audit

The site migration process begins with a thorough technical audit. This establishes the baseline for you to reference after the migration to see the overall site health and performance.  

At Crowdlinker, we see the migration process as an opportunity to improve a website's SEO and lay the seeds which will act as a catalyst for all on-going SEO efforts made post-migration. More specifically, we want to compare the website’s crawlability, indexability, and visibility post-migration, therefore, we track certain key performance indicators (KPIs) through the technical audit.  

The technical site audit will include the points listed below, in addition to many others depending on the website:

  • Duplicate Content
  • Missing Metadata
  • Unoptimized Metadata
  • HTTP Status Codes (404, 301, 302, etc.)
  • Internal Linking
  • On-­page Factors
  • Site Speed
  • Site Navigation
  • Site Security
  • Mobile­-Friendliness

URL Mapping

The second step of our “pre-launch” site migration agenda includes URL Mapping. In this step, we suggest using specialized tools like Screaming Frog or SEMRush to scrape your entire website and organize all the URLs in one spreadsheet.

This spreadsheet will be used throughout the migration journey and will become the main point of reference for 301 redirects, canonicalization, pixels, and other important elements of the page like metadata (title tags, heading tags, etc.)

URL Redirection Plan

Your URL redirection plan is quite possibly the most important step of the website migration process from an SEO perspective. Special precautions will need to be taken in order to ensure the proper implementation of this task.

The redirects should be implemented on a page to page basis, meaning there shouldn’t be any “bulk redirects” to the home page, which could result in search engines devaluing the authority of the page and website as a whole.  

Moreover, all redirected URLs should also go to the new URLs that have the exact same content or at least a thematically related page on the website.

Quick tip: Set up all URL redirects on the server side to ensure they don't cost the site any speed.

Click here to review source.

Canonicalization Plan

Forgetting to change the canonical tags from the old URLs to the new can confuse search engines, slow down indexing and can lead to a loss in authority for the overall domain. This is the reason you should set site-wide self-referencing canonicals in addition to making sure pages that canonicalize different pages are updated with the new URLs.

On-Page Plan

When you do a website migration onto another platform or change the website's HTML at any capacity you change the way that search bots interact with your website. Therefore, it is important to consider the following HTML factors that search bots give the most value to and try to keep them consistent with the old website (unless you are optimizing them).

  • Information Hierarchy
  • Title Tags
  • Meta Descriptions
  • Heading Tags
  • Body Copy - bold, underlines, italics, font size, etc.
  • Image optimization
  • Structured data

Internal Linking Plan

Internal linking is an especially important on-page procedure to consider when doing a site migration. Apart from basics like updating links in the main navigation and footer with new URLs, body text links also need to be updated accordingly.


Other SEO elements that need to be taken into consideration include:

Migrating Tracking Code

Ensure all tracking code/pixels are transferred over to the new platform, including but not limited to Google Tag Manager, GA, Search Console, AdWords, Facebook, etc.

External Links

Change external links from social media, directories and affiliate websites that your website has control over. Although they will get redirected if they are left unchanged, it’s just good house-keeping.


Set up benchmark metrics to compare the website after migration. Apart from having site health metrics, a complete list of backlinks, current ranking keywords, and traffic stats are also important data to keep handy.


During the launch, there will be a migration window which typically lasts between 7-10 days after the switch is finalized and the website is live. In this time, the following steps are important to take:

Keep a close eye on Search Console and Google Analytics

A site migration will almost always result in a temporary loss of traffic as the search bots take their time to consume the new HTML and update their indexes for new URLs and redirects. The goal for any site migration is, therefore, to reduce traffic fluctuations and increase the rate at which search engines recognize the new site as if it were the original.

Click here to review source.

Resubmitting sitemap to all webmaster properties

Once the website is live and removes the “nofollow” tags which kept the search bots from crawling the staging website, the next step is to submit the new sitemap and “fetch as Google.”


Once the website is live and removes the “nofollow” tags which kept the search bots from crawling the staging website, the next step is to submit the new sitemap and “fetch as Google.”


The migration process should end, from the SEO perspective, with a detailed site audit. You should be comparing one to one, technical, ranking and traffic metrics we documented in the pre-launch stage to evaluate our progress and next steps.

Special Considerations

Below is a list of special considerations you might also want to take in order to further boost your site health after the migration:

URLs With High Authority Backlinks

When confronted with a URL that has high authority backlinks but is set to change its URL, you might want to contact the backlink giver and ask them to change the URL that they are linking to in order to reflect the new page.

Increase Paid Traffic Budget

It is wise to increase ad spending for a short period of time after the migration. This way more visitors will land on the website which will encourage search bots to crawl it with more frequency. Moreover, with increased engagement (scroll rate, time on site, page views per visit) search bots will increase the authority of the website as a whole.

SEO Tips

Like mentioned before, Crowdlinker views website migrations as an opportunity to increase search engine optimization. As a result, we wanted to share some quick-win suggestions you can consider:

Upgrade SSL

Your company might decide to use this migration as an opportunity to upgrade their SSL certificate. Although, your website might already be secure, upgrading the SSL, for example from a Domain Validated SSL to Extended Validated SSL will make your domain more trustworthy in the eyes of your visitors and also increase conversion rates.

Theming & Conflicting Pages

During the migration process, your company can also look to explore any internal theming or page conflicts. This might mean consolidating thin pages into one comprehensive page or canonicalizing two conflicting pages competing for the same keyword. Doing this will help build your website authority as well as breakthrough any glass ceiling that has hindered your search engine rankings.  

Internal Linking

Lastly, your company might take this opportunity to improve your internal linking strategy. Improved internal linking will help your website trust flow, as well as help search bots make better sense of the website through collective content (linking to similar content in body with anchor text rich keywords).


Migrating a website is a complicated and risky procedure. Regardless of how well the process is planned and executed, you can expect a slight drop off in search engine traffic in most cases. Our aim with this article was to better equip companies looking to migrate websites that are motivated to keep their hard earned search engine website traffic. With the suggestions above, we hope you too can migrate your website with fewer glitches.

For more information about migrating your company website without losing your search engine traffic, reach out to Crowdlinker.

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