Export InfoPath forms from SharePoint Online
Before you can archive, convert or even read an InfoPath library, you need its files on a disk. SharePoint gives you three reasonable ways to get them there.
To export InfoPath forms from SharePoint Online, download the submission .xml files from the form library and the template from the library's Forms folder (usually template.xsn). For a few hundred forms, select them in the library and click Download. For larger libraries, sync the library with OneDrive or use PnP PowerShell to download every file, which also keeps folder structure intact. Then open the files in FormArchive to export them to PDF and Excel.
Option 1: download from the library
Open the form library, switch to a view that shows all items without folders or filters, select the forms, and choose Download. Several files arrive as a single zip. This is the quickest route for a small library. For a large one, downloads can be slow, and you have to make sure the view really shows every item.
Option 2: sync with OneDrive
Use the library's Sync button to mirror it into File Explorer or Finder through the OneDrive client. Set the folder to always keep files on the device so the content is actually downloaded, not just placeholders. Sync preserves folders and resumes on its own if the connection drops, which makes it the easiest route for libraries of several thousand forms.
Option 3: PowerShell
For many libraries, or for a repeatable archive run, PnP PowerShell can connect to a site and download every file in a library to a local folder, recursing through subfolders. Script it once and run it for each library on your inventory list, writing a log of what was downloaded. Your admin may need to approve the PnP app registration for your tenant first.
Don't forget the template
The form layout is not in the submissions. In a form library, the template is usually at Forms/template.xsn; libraries that use content types may keep it with the content type. If you can't find it, the first line of any submission contains an href pointing to where the template was published. Without it, FormArchive still opens every form in a generic view.
Open your InfoPath forms now
Drop in the template and a folder of submissions. Preview 10 forms free, on your own computer.
FAQ
Where is the InfoPath template in SharePoint?
Usually in the form library's Forms folder, as template.xsn. Each submission's first line also records the template's published location.
Will SharePoint's Export to Excel give me the form data?
Only the promoted columns. Fields that were never promoted exist only inside each XML file.
Do I need admin rights to export?
Read access to the library is enough to download its files. PowerShell may need an app approved by your admin.