So here is a list of very informative URLs "hidden" in SharePoint.
Just substitute your site collection URL for http://intranet.contoso.com, http://siteurl, or http://yourservername/sites/yoursite/
Office 365 (11.16.2018)
More from the cloud engineer
http://thecloudengineer.blogspot.com/2018/11/office-365-hidden-or-secret-urls.html
SharePoint
Site Content and Structure
http://intranet.contoso.com/_layouts/sitemanager.aspxUser Information List
http://intranet.contoso.com/_catalogs/users/simple.aspx
http://intranet.contoso.com/_catalogs/users/detail.aspx
http://intranet.contoso.com/_layouts/15/people.aspx?MembershipGroupId=0
Logon As Different User
http://support.microsoft.com/kb/2752600- Start Internet Explorer by using the Run as different user option, and then go to the SharePoint site.
Note: The Run as different user option is visible if you hold the Shift key when you right-click a program icon. - Access the SharePoint site by using the the URL as http://siteurl/_layouts/closeConnection.aspx?loginasanotheruser=true
- Firefox Multi User Add-On such as multifox
https://addons.mozilla.org/en-US/firefox/addon/multifox/
Miss the Old List and Library Interface?
http://yourservername/sites/yoursite/_layouts/create.aspx
Slide Library (Manual link required)
Use this link http://yourserver/sites/yoursite/_layouts/15/slnew.aspx?FeatureId={0be49fe9-9bc9-409d-abf9-702753bd878d}&ListTemplate=2100Thx Mike http://techtrainingnotes.blogspot.com/2012/11/finding-missing-sharepoint-2013-slide.html
Site-Collection > Web Analytics Report - Summary
http://intranet.contoso.com/_layouts/usage.aspx
Taxonomy
http://yoursite/Lists/TaxonomyHiddenList
User Profile (Hybrid)
http://mysites.contoso.com/person.aspx?NoRedirect=Yes
User Profile Photos
http://userprofielurl/User%20Photos/Forms/AllItems.aspx
Not Hidden - Important URLs
Site Collection Administration > Storage Metrics (new to SP1)http://intranet.contoso.com/_layouts/stor.aspx
People and Groups Set Up
http://intranet.contoso.com/_layouts/15/permsetup.aspxWeb Part Maintenance Page
http://intranet.contoso.com?contents=1Just add ? contents=1 after any page.
https://support.office.com/en-us/article/Open-and-use-the-Web-Part-Maintenance-Page-eff9ce22-d04a-44dd-ae83-ac29a5e396c2