I am nowhere near a professional photographer but still I have a massive 70+ GB photo library which is taking up lots of space on my 2017 MBP. But I only need a fraction of the library on a regular basis. Is there an alternative to the Photos app out there that let me offload -> parts <- of my library to an external drive but leave thumbnails (or low res versions) when browsing without having the external drive connected? I have a faint memory that either Aperture or Lightroom had such a feature. Now Aperture was discontinued and I don't need the pro features/price tag of Lightroom. There must be a photos app out there that lets me partially store my photos on an external drive while allowing me to browse lowres/thumbails even when its not connected, right?