Notes about the SPDESIGNTXT file extension:
To open this file type, a required software must be installed. Without it you only see a Windows message "The following file cannot be opened
" (Windows 7) or "How do you want to open this file?
" (Windows 10) if you double-click the file. There click on "More apps"
and choose a suitable software to view such files on your PC or from email attachments.
The SPDESIGNTXT file type is primarily associated with 'SharePoint Designer' by Microsoft Corporation. Office SharePoint Designer provides tools to automate business processes, build efficient applications on top of the Microsoft SharePoint platform, and tailor SharePoint sites.