No, using the free companion SimpleTransfer Desktop is completely optional.
However, it offers some extra options (e.g. ability to use USB cable for faster transfer, change the location of transferred files and not having to zip downloaded files), which are not available on the web browser version.
Note that the Desktop app is currently available for Windows and macOS. Linux is not supported yet, however you can use the web browser method instead.
HEIC is the file extension for new photo format introduced in iOS 11.0 to reduce file size and is used almost on all new iPhone and iPad devices. HEIF and HEVC files are supported by default on newer version of macOS but not on Windows and older versions of macOS. Simple Transfer allows you to convert HEIC file to JPG in the download screen.
This usually happens on Windows where it does not support playing the new High Efficiency video format (HEVC) recorded on iPhone. In this case, select H.264 for Video Format on the download page.
When you delete photos and videos, they are temporarily moved to the Recently Deleted album on your Photos app and stay there for 30 days. You can use the Photos app to recover them from the Recently Deleted album.
If you have already purchased the Pro version, you don't need to pay again when you delete/reinstall your app. Just open the Simple Transfer app and select Restore Purchase option from the Settings tab of the app. Then enter the same Apple ID you used to upgrade the app.
All the downloaded photos are saved in the default Downloads folder of your computer (the same location where downloaded files from the Internet are saved). You can always change the default location from the Settings screen of your web browser.
When you select more than one item to download, Simple Transfer automatically puts them in zip file in order to preserve the file timestamp (it's not possible to change datetime of a downloaded file from web browser). If you do not want to download the items as zip file, you can use the free SimpleTransfer Desktop companion app.
This is because Photos app never duplicates photos when you add them to another album. Instead, it just adds a link to that photo. This is why if you delete a photo from an album (other than Camera Roll) the original version which is stored in Camera Roll never gets deleted. But if you delete a photo from Camera Roll, it will be deleted from all other albums too.
Unfortunately Apple does not support sharing in-app purchases with family members (even if it's stated in the app description). Note that everything related to the App Store payment system including family sharing is handled by Apple (not developers). Please refer this this page for more info
Both apps are identical in terms of functionality. The only difference between the two is their pricing and Family Sharing:
This is because Simple Transfer does not use a public website hosted on the Internet. The website is just hosted on your iPhone/iPad locally, which is why all of your photos and videos are transferred only in your local WiFi network. You can safely ignore this warning.
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