sips
is already on your Mac. I have no experience using it with PSD files, but I do use it to batch convert other image files all the time. What I do is:
- Copy all the files I want to convert to a new folder.
- In the new folder, change the extensions of all the files to whatever’s appropriate for the format they will be changed to. In your case, that would be
png
. You can do that in one step by selecting all the files and using the Rename command from the right-click menu. - Open Terminal,
cd
to the new folder, and runsips -s format png *
Done.