Overview

You would like to check for broken or outdated links. You are looking for a tool that could scan your site and flag broken links. 

Solution

Check-SPOBrokenLink detects and lists all broken links within SharePoint Online sites and can be downloaded here.

The provider of this tool has it listed here. 

How to Use it

1. Download all the files a put them all in the same directory.
2. Set variables according to your environment.
3. Set a test filter in $TenantSites.
4. Set a test filter in $TenantSitePages.

Next Improvement Steps

1. Find a better regex pattern to identify URL.
2. Consider using ConvertFrom-Json to obtain an object of the page's content.
3. Currently, only pages are checked, we need to look in lists too.
4. Improve code in general.

The above tool requires in-depth knowledge and customization. If you are looking for other approaches, please try the following sites.

• https://www.replacemagic.com/
• https://spandcrm.com/2016/09/08/qipoint-broken-link-manager-review-and-how-to/
• https://spandcrm.com/2015/03/16/checking-for-broken-links-in-sharepoint-2013/
• https://social.technet.microsoft.com/Forums/en-US/304cc75b-19e9-4ef2-b927-272032357dd2/is-there-a-scripttool-to-find-broken-links?forum=sharepointadmin
• https://sharepoint.stackexchange.com/questions/195007/sp13-broken-link-scan
• SharePoint Online - Check for broken links | Blog Please Do IT For Me (p-difm.com)

Microsoft's free tool is "Search Engine Optimization Toolkit." Please note that these may be third-party tools so run them carefully after verifying that they are valid and will not harm your site.