It's not really free for personal use > https://www.highmotionsoftware.com/order/imbatch , the "free" version is limited to one thread, you have to pay to unlock it... 
I don't agree with their statement.
It's more than 20 years that XnView / XnConvert are doing it (just to name one), and not only for the Microsoft' Windows system...
All XnThings are multi-platform > Linux, macOS and M$'s Windows, truly free for personal use multi-threaded (it's freak'n fast), no limitation because it's the very same software you download for every-one as you just pay a license if you have to and will NOT unlock something when you input it in the software, also cheaper if you have to buy a license
Exclusive M$ Windows, you have IrfanView and FastStone if my memory don't fail, and are in the same league about license than XnView (no restriction for personal use).
Quote:What makes this tool different from other batch image processors is its “Task Structure”. You can combine Tasks to make a processing sequence that will give you exactly what you want.
I don't agree with their statement.
It's more than 20 years that XnView / XnConvert are doing it (just to name one), and not only for the Microsoft' Windows system...
All XnThings are multi-platform > Linux, macOS and M$'s Windows, truly free for personal use multi-threaded (it's freak'n fast), no limitation because it's the very same software you download for every-one as you just pay a license if you have to and will NOT unlock something when you input it in the software, also cheaper if you have to buy a license
Exclusive M$ Windows, you have IrfanView and FastStone if my memory don't fail, and are in the same league about license than XnView (no restriction for personal use).
Patrice