I was looking for discussions mentioning this app on HN, but didn’t find any. I am not affiliated with it, just thought I’d bring it to the community’s attention as I have been using for more than a year with my NAS, remotely over SFTP. It is a rare example of a very well thought through application, thoroughly executed: all it does is transfer photos to or from my devices and any thinkable destination. Highly configurable.
